const std = @import("std");
const allocator = std.heap.c_allocator;

const panto = @import("panto");

var threaded: ?std.Io.Threaded = null;
threadlocal var last_error: ?[]u8 = null;

const PantoAgent = opaque {};
const PantoStream = opaque {};
const PantoConversation = opaque {};
const PantoSession = opaque {};
const PantoSessionStore = opaque {};

const AgentHandle = struct { agent: *panto.Agent, config: *panto.Config };
const ConversationHandle = struct { conversation: panto.Conversation };
const SessionHandle = struct { session: panto.Session, owns_info: bool = true };
const StoreHandle = struct { ctx: *anyopaque, vtable: *const PantoSessionStoreVTable };
const NullStoreHandle = struct { store: panto.NullStore };
const FileSystemJSONLStoreHandle = struct { store: panto.FileSystemJSONLStore };
const ToolHandle = struct { ctx: *anyopaque, invoke: PantoToolInvokeFn, destroy: ?PantoToolDestroyFn, decl: panto.ToolDecl };
const ToolSourceHandle = struct { ctx: *anyopaque, invoke_batch: PantoToolSourceInvokeBatchFn, destroy: ?PantoToolDestroyFn, name: []u8, decls: []panto.ToolDecl };

pub const PantoSlice = extern struct { ptr: ?[*]const u8, len: usize };
pub const PantoStatus = enum(c_int) { ok = 0, err = 1 };
pub const PantoNextStatus = enum(c_int) { event = 0, done = 1, err = 2 };
pub const PantoAPIStyle = enum(c_int) { openai_chat = 0, anthropic_messages = 1 };
pub const PantoReasoningEffort = enum(c_int) { default = 0, off, minimal, low, medium, high };
pub const PantoThinking = enum(c_int) { disabled = 0, enabled, adaptive };
pub const PantoEffort = enum(c_int) { low = 0, medium, high, xhigh, max };
pub const PantoMessageRole = enum(c_int) { system = 0, user, assistant };
pub const PantoContentBlockTag = enum(c_int) { Text = 0, Thinking, ToolUse, ToolResult, System, CompactionSummary };
pub const PantoSystemMode = enum(c_int) { append = 0, replace };
pub const PantoEventTag = enum(c_int) { message_start = 0, block_start, tool_details, content_delta, block_complete, message_complete, provider_retry, tool_dispatch_start, tool_dispatch_complete, turn_complete };

pub const PantoUsage = extern struct { input: u64, output: u64, cache_read: u64, cache_write: u64, reasoning: u64 };
pub const PantoSessionInfo = extern struct { id: PantoSlice, created: PantoSlice, modified: PantoSlice, last_user_message: PantoSlice, base_url: PantoSlice, model: PantoSlice, message_count: usize, api_style: PantoAPIStyle, reasoning: PantoReasoningEffort };
pub const PantoSessionInfoList = extern struct { ptr: ?[*]PantoSessionInfo, len: usize };
pub const PantoSessionResult = extern struct { found: bool, session: ?*PantoSession };
pub const PantoOpenAIChatConfig = extern struct { api_key: ?[*:0]const u8, base_url: ?[*:0]const u8, model: ?[*:0]const u8, reasoning: PantoReasoningEffort, max_tokens: u32 };
pub const PantoAnthropicMessagesConfig = extern struct { api_key: ?[*:0]const u8, base_url: ?[*:0]const u8, model: ?[*:0]const u8, api_version: ?[*:0]const u8, max_tokens: u32, thinking: PantoThinking, effort: PantoEffort, has_thinking_budget_tokens: bool, thinking_budget_tokens: u32, thinking_interleaved: bool };
pub const PantoProviderConfig = extern struct { tag: PantoAPIStyle, data: extern union { openai_chat: PantoOpenAIChatConfig, anthropic_messages: PantoAnthropicMessagesConfig } };
pub const PantoCompactionConfig = extern struct { keep_verbatim: u32, has_model: bool, model: PantoProviderConfig, has_compaction_prompt: bool, compaction_prompt: ?[*:0]const u8 };
pub const PantoRetryConfig = extern struct { max_attempts: usize, initial_delay_ms: u64, max_delay_ms: u64, multiplier: f64, jitter: bool };
pub const PantoConfig = extern struct { provider: PantoProviderConfig, compaction: PantoCompactionConfig, retry: PantoRetryConfig };

pub const PantoBlockStart = extern struct { block_type: PantoContentBlockTag, index: usize };
pub const PantoToolDetails = extern struct { index: usize, id: PantoSlice, name: PantoSlice };
pub const PantoContentDelta = extern struct { index: usize, delta: PantoSlice };
pub const PantoBlockComplete = extern struct { index: usize, block_type: PantoContentBlockTag };
pub const PantoMessageComplete = extern struct { has_usage: bool, usage: PantoUsage };
pub const PantoCompactionResult = extern struct { compacted: bool, kept_turns: usize, summarized_messages: usize };
pub const PantoProviderRetry = extern struct { attempt: usize, max_attempts: usize, delay_ms: u64, error_name: PantoSlice, has_status_code: bool, status_code: u16, has_retry_after_ms: bool, retry_after_ms: u64, message: PantoSlice, compaction: bool };
pub const PantoToolDispatchStart = extern struct { count: usize };
pub const PantoToolDispatchComplete = extern struct { message_index: usize };
pub const PantoEvent = extern struct { tag: PantoEventTag, data: extern union { message_start: PantoMessageRole, block_start: PantoBlockStart, tool_details: PantoToolDetails, content_delta: PantoContentDelta, block_complete: PantoBlockComplete, message_complete: PantoMessageComplete, provider_retry: PantoProviderRetry, tool_dispatch_start: PantoToolDispatchStart, tool_dispatch_complete: PantoToolDispatchComplete } };
pub const PantoPersistentMessage = extern struct { role: PantoMessageRole, has_usage: bool, usage: PantoUsage, has_metadata: bool, metadata: PantoSlice };
pub const PantoSessionStoreVTable = extern struct {
    create: *const fn (*anyopaque, **PantoSession) callconv(.c) PantoStatus,
    list: *const fn (*anyopaque, *PantoSessionInfoList) callconv(.c) PantoStatus,
    free_session_infos: *const fn (*anyopaque, PantoSessionInfoList) callconv(.c) void,
    resolve: *const fn (*anyopaque, PantoSlice, *PantoSessionResult) callconv(.c) PantoStatus,
    latest: *const fn (*anyopaque, *PantoSessionResult) callconv(.c) PantoStatus,
    load: *const fn (*anyopaque, PantoSlice, **PantoConversation) callconv(.c) PantoStatus,
    append_messages: *const fn (*anyopaque, PantoSlice, [*]const PantoPersistentMessage, usize) callconv(.c) PantoStatus,
    destroy: ?*const fn (*anyopaque) callconv(.c) void,
};
pub const PantoToolDecl = extern struct { name: PantoSlice, description: PantoSlice, schema_json: PantoSlice };
pub const PantoMediaPart = extern struct { media_type: PantoSlice, has_media_type: bool, data: PantoSlice };
pub const PantoResultPartTag = enum(c_int) { text = 0, media = 1 };
pub const PantoResultPart = extern struct { tag: PantoResultPartTag, data: extern union { text: PantoSlice, media: PantoMediaPart } };
pub const PantoResultParts = extern struct { ptr: ?[*]PantoResultPart, len: usize };
pub const PantoToolCall = extern struct { tool_name: PantoSlice, input: PantoSlice };
pub const PantoToolCallResult = extern struct { ok: bool, parts: PantoResultParts, err: PantoSlice };
pub const PantoToolInvokeFn = *const fn (*anyopaque, PantoSlice, *PantoResultParts) callconv(.c) PantoStatus;
pub const PantoToolSourceInvokeBatchFn = *const fn (*anyopaque, [*]const PantoToolCall, [*]PantoToolCallResult, usize) callconv(.c) PantoStatus;
pub const PantoToolDestroyFn = *const fn (*anyopaque) callconv(.c) void;

fn setErr(comptime fmt: []const u8, args: anytype) PantoStatus {
    setErrVoid(fmt, args);
    return .err;
}
fn setErrNext(comptime fmt: []const u8, args: anytype) PantoNextStatus {
    setErrVoid(fmt, args);
    return .err;
}
fn setErrVoid(comptime fmt: []const u8, args: anytype) void {
    if (last_error) |e| allocator.free(e);
    last_error = std.fmt.allocPrint(allocator, fmt, args) catch null;
}
fn slice(s: PantoSlice) []const u8 {
    return if (s.ptr) |p| p[0..s.len] else &.{};
}
fn outSlice(s: []const u8) PantoSlice {
    return .{ .ptr = s.ptr, .len = s.len };
}
fn dupSlice(s: PantoSlice) ![]u8 {
    return allocator.dupe(u8, slice(s));
}
fn cstr(s: ?[*:0]const u8) []const u8 {
    return if (s) |p| std.mem.span(p) else &.{};
}
fn dupCStr(s: ?[*:0]const u8) ![]u8 {
    return allocator.dupe(u8, cstr(s));
}
fn dupOut(s: []const u8) !PantoSlice {
    return outSlice(try allocator.dupe(u8, s));
}
fn cloneSessionInfo(info: PantoSessionInfo) !panto.SessionInfo {
    return .{ .id = try dupSlice(info.id), .created = try dupSlice(info.created), .modified = try dupSlice(info.modified), .message_count = info.message_count, .last_user_message = try dupSlice(info.last_user_message), .api_style = @enumFromInt(@intFromEnum(info.api_style)), .base_url = try dupSlice(info.base_url), .model = try dupSlice(info.model), .reasoning = @enumFromInt(@intFromEnum(info.reasoning)) };
}
fn marshalSessionInfo(info: panto.SessionInfo) !PantoSessionInfo {
    return .{ .id = try dupOut(info.id), .created = try dupOut(info.created), .modified = try dupOut(info.modified), .last_user_message = try dupOut(info.last_user_message), .base_url = try dupOut(info.base_url), .model = try dupOut(info.model), .message_count = info.message_count, .api_style = @enumFromInt(@intFromEnum(info.api_style)), .reasoning = @enumFromInt(@intFromEnum(info.reasoning)) };
}
fn freePantoSessionInfo(info: PantoSessionInfo) void {
    freePS(info.id);
    freePS(info.created);
    freePS(info.modified);
    freePS(info.last_user_message);
    freePS(info.base_url);
    freePS(info.model);
}
fn wrapSession(session: panto.Session, owns_info: bool) !*PantoSession {
    const h = try allocator.create(SessionHandle);
    h.* = .{ .session = session, .owns_info = owns_info };
    return @ptrCast(h);
}
fn unwrapStore(store: *PantoSessionStore) panto.SessionStore {
    return .{ .ptr = store, .vtable = &c_store_vtable };
}

export fn panto_init() void {
    if (threaded == null) {
        threaded = std.Io.Threaded.init(allocator, .{});
        panto.init(allocator, threaded.?.io());
    }
}
export fn panto_deinit() void {
    panto.deinit();
    if (threaded) |*t| t.deinit();
    threaded = null;
}
export fn panto_last_error() PantoSlice {
    return if (last_error) |e| outSlice(e) else .{ .ptr = null, .len = 0 };
}
export fn panto_error_free(s: PantoSlice) void {
    if (s.ptr) |p| allocator.free(@constCast(p[0..s.len]));
}

export fn panto_conversation_create(out: **PantoConversation) PantoStatus {
    const h = allocator.create(ConversationHandle) catch return setErr("OutOfMemory", .{});
    h.* = .{ .conversation = panto.Conversation.init(allocator) };
    out.* = @ptrCast(h);
    return .ok;
}
export fn panto_conversation_destroy(c: ?*PantoConversation) void {
    if (c) |ptr| {
        const h: *ConversationHandle = @ptrCast(@alignCast(ptr));
        h.conversation.deinit();
        allocator.destroy(h);
    }
}
fn unwrapConversation(c: *PantoConversation) *panto.Conversation {
    return &(@as(*ConversationHandle, @ptrCast(@alignCast(c))).conversation);
}
fn msgAt(c: *PantoConversation, index: usize) ?*panto.Message {
    const cc = unwrapConversation(c);
    if (index >= cc.messages.items.len) return null;
    return &cc.messages.items[index];
}
fn blockAt(c: *PantoConversation, mi: usize, bi: usize) ?*panto.ContentBlock {
    const m = msgAt(c, mi) orelse return null;
    if (bi >= m.content.items.len) return null;
    return &m.content.items[bi];
}
export fn panto_conversation_message_count(c: *PantoConversation) usize {
    return unwrapConversation(c).messages.items.len;
}
export fn panto_conversation_message_role(c: *PantoConversation, index: usize) PantoMessageRole {
    const m = msgAt(c, index) orelse return .user;
    return @enumFromInt(@intFromEnum(m.role));
}
export fn panto_conversation_message_has_usage(c: *PantoConversation, index: usize) bool {
    const m = msgAt(c, index) orelse return false;
    return m.usage != null;
}
export fn panto_conversation_message_usage(c: *PantoConversation, index: usize) PantoUsage {
    const m = msgAt(c, index) orelse return .{ .input = 0, .output = 0, .cache_read = 0, .cache_write = 0, .reasoning = 0 };
    return if (m.usage) |u| usage(u) else .{ .input = 0, .output = 0, .cache_read = 0, .cache_write = 0, .reasoning = 0 };
}
export fn panto_conversation_message_block_count(c: *PantoConversation, index: usize) usize {
    const m = msgAt(c, index) orelse return 0;
    return m.content.items.len;
}
export fn panto_conversation_block_tag(c: *PantoConversation, mi: usize, bi: usize) PantoContentBlockTag {
    const b = blockAt(c, mi, bi) orelse return .Text;
    return @enumFromInt(@intFromEnum(b.*));
}
export fn panto_conversation_block_text(c: *PantoConversation, mi: usize, bi: usize) PantoSlice {
    const b = blockAt(c, mi, bi) orelse return .{ .ptr = null, .len = 0 };
    return switch (b.*) {
        .Text => |t| outSlice(t.items),
        .Thinking => |t| outSlice(t.text.items),
        .ToolUse => |t| outSlice(t.input.items),
        .ToolResult => |tr| blk: {
            for (tr.parts.items) |p| if (p == .text) break :blk outSlice(p.text.items);
            break :blk .{ .ptr = null, .len = 0 };
        },
        .System => |s| outSlice(s.text.items),
        .CompactionSummary => |s| outSlice(s.text.items),
    };
}
export fn panto_conversation_block_tool_id(c: *PantoConversation, mi: usize, bi: usize) PantoSlice {
    const b = blockAt(c, mi, bi) orelse return .{ .ptr = null, .len = 0 };
    return switch (b.*) { .ToolUse => |t| outSlice(t.id), .ToolResult => |t| outSlice(t.tool_use_id), else => .{ .ptr = null, .len = 0 } };
}
export fn panto_conversation_block_tool_name(c: *PantoConversation, mi: usize, bi: usize) PantoSlice {
    const b = blockAt(c, mi, bi) orelse return .{ .ptr = null, .len = 0 };
    return switch (b.*) { .ToolUse => |t| outSlice(t.name), else => .{ .ptr = null, .len = 0 } };
}
export fn panto_conversation_block_tool_result_is_error(c: *PantoConversation, mi: usize, bi: usize) bool {
    const b = blockAt(c, mi, bi) orelse return false;
    return switch (b.*) { .ToolResult => |t| t.is_error, else => false };
}
export fn panto_conversation_block_system_mode(c: *PantoConversation, mi: usize, bi: usize) PantoSystemMode {
    const b = blockAt(c, mi, bi) orelse return .append;
    return switch (b.*) { .System => |s| @enumFromInt(@intFromEnum(s.mode)), else => .append };
}
export fn panto_conversation_add_system_message(c: *PantoConversation, text: ?[*:0]const u8) PantoStatus {
    unwrapConversation(c).addSystemMessage(cstr(text)) catch |e| return setErr("{t}", .{e});
    return .ok;
}
export fn panto_conversation_replace_system_message(c: *PantoConversation, text: ?[*:0]const u8) PantoStatus {
    unwrapConversation(c).replaceSystemMessage(cstr(text)) catch |e| return setErr("{t}", .{e});
    return .ok;
}
export fn panto_conversation_add_user_text(c: *PantoConversation, text: ?[*:0]const u8) PantoStatus {
    const cc = unwrapConversation(c);
    const tb = panto.textualBlockFromSlice(cc.allocator, cstr(text)) catch |e| return setErr("{t}", .{e});
    const b: panto.ContentBlock = .{ .Text = tb };
    cc.addUserMessage(&.{b}) catch |e| return setErr("{t}", .{e});
    return .ok;
}
export fn panto_conversation_add_assistant_text(c: *PantoConversation, text: ?[*:0]const u8, has_usage: bool, u: PantoUsage) PantoStatus {
    const cc = unwrapConversation(c);
    const tb = panto.textualBlockFromSlice(cc.allocator, cstr(text)) catch |e| return setErr("{t}", .{e});
    const b: panto.ContentBlock = .{ .Text = tb };
    cc.addAssistantMessage(&.{b}, if (has_usage) zigUsage(u) else null) catch |e| return setErr("{t}", .{e});
    return .ok;
}
export fn panto_conversation_add_compaction_summary(c: *PantoConversation, text: ?[*:0]const u8) PantoStatus {
    unwrapConversation(c).addCompactionSummary(cstr(text)) catch |e| return setErr("{t}", .{e});
    return .ok;
}
export fn panto_session_create_null(out: **PantoSession) PantoStatus {
    const h = allocator.create(SessionHandle) catch return setErr("OutOfMemory", .{});
    var ns = panto.NullStore.init(allocator);
    h.* = .{ .session = ns.store().create() };
    out.* = @ptrCast(h);
    return .ok;
}
export fn panto_session_create(store: *PantoSessionStore, info: PantoSessionInfo, out: **PantoSession) PantoStatus {
    const cloned = cloneSessionInfo(info) catch |e| return setErr("{t}", .{e});
    out.* = wrapSession(.{ .info = cloned, .store = unwrapStore(store) }, true) catch |e| return setErr("{t}", .{e});
    return .ok;
}
export fn panto_session_destroy(s: ?*PantoSession) void {
    if (s) |ptr| {
        const h: *SessionHandle = @ptrCast(@alignCast(ptr));
        if (h.owns_info) h.session.info.deinit(allocator);
        allocator.destroy(h);
    }
}
export fn panto_session_store_create(ctx: *anyopaque, vt: *const PantoSessionStoreVTable, out: **PantoSessionStore) PantoStatus {
    const h = allocator.create(StoreHandle) catch return setErr("OutOfMemory", .{});
    h.* = .{ .ctx = ctx, .vtable = vt };
    out.* = @ptrCast(h);
    return .ok;
}
export fn panto_session_store_destroy(store: ?*PantoSessionStore) void {
    if (store) |ptr| {
        const h: *StoreHandle = @ptrCast(@alignCast(ptr));
        if (h.vtable.destroy) |d| d(h.ctx);
        allocator.destroy(h);
    }
}
export fn panto_null_store_create(out: **PantoSessionStore) PantoStatus {
    const impl = allocator.create(NullStoreHandle) catch return setErr("OutOfMemory", .{});
    impl.* = .{ .store = panto.NullStore.init(allocator) };
    const h = allocator.create(StoreHandle) catch {
        allocator.destroy(impl);
        return setErr("OutOfMemory", .{});
    };
    h.* = .{ .ctx = &impl.store, .vtable = &null_store_vtable };
    out.* = @ptrCast(h);
    return .ok;
}
export fn panto_file_system_jsonl_store_create(dir: ?[*:0]const u8, metadata: ?[*:0]const u8, out: **PantoSessionStore) PantoStatus {
    const impl = allocator.create(FileSystemJSONLStoreHandle) catch return setErr("OutOfMemory", .{});
    impl.* = .{ .store = panto.FileSystemJSONLStore.initWithMetadata(allocator, threaded.?.io(), cstr(dir), if (metadata == null or cstr(metadata).len == 0) null else cstr(metadata)) catch |e| {
        allocator.destroy(impl);
        return setErr("{t}", .{e});
    } };
    const h = allocator.create(StoreHandle) catch {
        impl.store.deinit();
        allocator.destroy(impl);
        return setErr("OutOfMemory", .{});
    };
    h.* = .{ .ctx = &impl.store, .vtable = &fs_jsonl_store_vtable };
    out.* = @ptrCast(h);
    return .ok;
}
export fn panto_session_store_create_session(store: *PantoSessionStore, out: **PantoSession) PantoStatus {
    return cStoreCreate(store, out);
}
export fn panto_session_store_list(store: *PantoSessionStore, out: *PantoSessionInfoList) PantoStatus {
    return cStoreList(store, out);
}
export fn panto_session_info_list_destroy(infos: PantoSessionInfoList) void {
    if (infos.ptr) |p| {
        for (p[0..infos.len]) |info| freePantoSessionInfo(info);
        allocator.free(p[0..infos.len]);
    }
}
export fn panto_session_store_resolve(store: *PantoSessionStore, id: ?[*:0]const u8, out: *PantoSessionResult) PantoStatus {
    return cStoreResolve(store, outSlice(cstr(id)), out);
}
export fn panto_session_store_latest(store: *PantoSessionStore, out: *PantoSessionResult) PantoStatus {
    return cStoreLatest(store, out);
}
export fn panto_session_load(session: *PantoSession, out: **PantoConversation) PantoStatus {
    const h: *SessionHandle = @ptrCast(@alignCast(session));
    const conv = h.session.load() catch |e| return setErr("{t}", .{e});
    const ch = allocator.create(ConversationHandle) catch return setErr("OutOfMemory", .{});
    ch.* = .{ .conversation = conv };
    out.* = @ptrCast(ch);
    return .ok;
}

fn convertConfig(c: *const PantoConfig) !*panto.Config {
    const out = try allocator.create(panto.Config);
    errdefer allocator.destroy(out);
    out.* = .{ .provider = try convertProvider(c.provider), .compaction = .{ .keep_verbatim = c.compaction.keep_verbatim, .model = if (c.compaction.has_model) try convertProvider(c.compaction.model) else null, .compaction_prompt = if (c.compaction.has_compaction_prompt) try dupCStr(c.compaction.compaction_prompt) else null }, .retry = .{ .max_attempts = c.retry.max_attempts, .initial_delay_ms = c.retry.initial_delay_ms, .max_delay_ms = c.retry.max_delay_ms, .multiplier = c.retry.multiplier, .jitter = c.retry.jitter } };
    return out;
}
fn convertProvider(p: PantoProviderConfig) !panto.ProviderConfig {
    return switch (p.tag) {
        .openai_chat => .{ .openai_chat = .{ .api_key = try dupCStr(p.data.openai_chat.api_key), .base_url = try dupCStr(p.data.openai_chat.base_url), .model = try dupCStr(p.data.openai_chat.model), .reasoning = @enumFromInt(@intFromEnum(p.data.openai_chat.reasoning)), .max_tokens = p.data.openai_chat.max_tokens } },
        .anthropic_messages => .{ .anthropic_messages = .{ .api_key = try dupCStr(p.data.anthropic_messages.api_key), .base_url = try dupCStr(p.data.anthropic_messages.base_url), .model = try dupCStr(p.data.anthropic_messages.model), .api_version = if (cstr(p.data.anthropic_messages.api_version).len == 0) "2023-06-01" else try dupCStr(p.data.anthropic_messages.api_version), .max_tokens = p.data.anthropic_messages.max_tokens, .thinking = @enumFromInt(@intFromEnum(p.data.anthropic_messages.thinking)), .effort = @enumFromInt(@intFromEnum(p.data.anthropic_messages.effort)), .thinking_budget_tokens = if (p.data.anthropic_messages.has_thinking_budget_tokens) p.data.anthropic_messages.thinking_budget_tokens else null, .thinking_interleaved = p.data.anthropic_messages.thinking_interleaved } },
    };
}
fn freeConfig(c: *panto.Config) void {
    freeProvider(&c.provider);
    if (c.compaction.model) |*m| freeProvider(m);
    if (c.compaction.compaction_prompt) |s| allocator.free(s);
    allocator.destroy(c);
}
fn freeProvider(pv: *panto.ProviderConfig) void {
    switch (pv.*) {
        .openai_chat => |c| {
            allocator.free(c.api_key);
            allocator.free(c.base_url);
            allocator.free(c.model);
        },
        .anthropic_messages => |c| {
            allocator.free(c.api_key);
            allocator.free(c.base_url);
            allocator.free(c.model);
            if (c.api_version.ptr != "2023-06-01".ptr) allocator.free(c.api_version);
        },
    }
}

fn cStoreCreate(ctx: *anyopaque, out: **PantoSession) PantoStatus {
    const h: *StoreHandle = @ptrCast(@alignCast(ctx));
    return h.vtable.create(h.ctx, out);
}
fn cStoreList(ctx: *anyopaque, out: *PantoSessionInfoList) PantoStatus {
    const h: *StoreHandle = @ptrCast(@alignCast(ctx));
    return h.vtable.list(h.ctx, out);
}
fn cStoreResolve(ctx: *anyopaque, id: PantoSlice, out: *PantoSessionResult) PantoStatus {
    const h: *StoreHandle = @ptrCast(@alignCast(ctx));
    return h.vtable.resolve(h.ctx, id, out);
}
fn cStoreLatest(ctx: *anyopaque, out: *PantoSessionResult) PantoStatus {
    const h: *StoreHandle = @ptrCast(@alignCast(ctx));
    return h.vtable.latest(h.ctx, out);
}
fn cStoreLoad(ctx: *anyopaque, id: []const u8) anyerror!?panto.Conversation {
    const h: *StoreHandle = @ptrCast(@alignCast(ctx));
    var out: *PantoConversation = undefined;
    if (h.vtable.load(h.ctx, outSlice(id), &out) != .ok) return error.CStoreLoadFailed;
    const ch: *ConversationHandle = @ptrCast(@alignCast(out));
    const conv = ch.conversation;
    ch.conversation = panto.Conversation.init(allocator);
    panto_conversation_destroy(out);
    return conv;
}
fn cStoreAppend(ctx: *anyopaque, session_id: []const u8, messages: []panto.PersistentMessage) anyerror!void {
    const h: *StoreHandle = @ptrCast(@alignCast(ctx));
    const cmsgs = try allocator.alloc(PantoPersistentMessage, messages.len);
    defer allocator.free(cmsgs);
    for (messages, 0..) |m, i| cmsgs[i] = .{ .role = @enumFromInt(@intFromEnum(m.message.role)), .has_usage = m.usage != null, .usage = if (m.usage) |u| usage(u) else .{ .input = 0, .output = 0, .cache_read = 0, .cache_write = 0, .reasoning = 0 }, .has_metadata = m.message.metadata != null, .metadata = outSlice(m.message.metadata orelse "") };
    if (h.vtable.append_messages(h.ctx, outSlice(session_id), cmsgs.ptr, cmsgs.len) != .ok) return error.CStoreAppendFailed;
}
fn cStoreListZ(ctx: *anyopaque) anyerror![]panto.SessionInfo {
    const h: *StoreHandle = @ptrCast(@alignCast(ctx));
    var list: PantoSessionInfoList = undefined;
    if (h.vtable.list(h.ctx, &list) != .ok) return error.CStoreListFailed;
    defer h.vtable.free_session_infos(h.ctx, list);
    const out = try allocator.alloc(panto.SessionInfo, list.len);
    errdefer allocator.free(out);
    if (list.ptr) |p| {
        for (p[0..list.len], 0..) |info, i| out[i] = try cloneSessionInfo(info);
    }
    return out;
}
fn cStoreFreeInfos(_: *anyopaque, infos: []panto.SessionInfo) void {
    for (infos) |info| info.deinit(allocator);
    allocator.free(infos);
}
fn cStoreResolveZ(ctx: *anyopaque, id: []const u8) anyerror!?panto.Session {
    const h: *StoreHandle = @ptrCast(@alignCast(ctx));
    var res: PantoSessionResult = undefined;
    if (h.vtable.resolve(h.ctx, outSlice(id), &res) != .ok) return error.CStoreResolveFailed;
    if (!res.found) return null;
    const sh: *SessionHandle = @ptrCast(@alignCast(res.session.?));
    return sh.session;
}
fn cStoreLatestZ(ctx: *anyopaque) anyerror!?panto.Session {
    const h: *StoreHandle = @ptrCast(@alignCast(ctx));
    var res: PantoSessionResult = undefined;
    if (h.vtable.latest(h.ctx, &res) != .ok) return error.CStoreLatestFailed;
    if (!res.found) return null;
    const sh: *SessionHandle = @ptrCast(@alignCast(res.session.?));
    return sh.session;
}
fn cStoreCreateZ(ctx: *anyopaque) panto.Session {
    var out: *PantoSession = undefined;
    if (cStoreCreate(ctx, &out) != .ok) {
        var ns = panto.NullStore.init(allocator);
        return ns.store().create();
    }
    const sh: *SessionHandle = @ptrCast(@alignCast(out));
    return sh.session;
}
const c_store_vtable: panto.SessionStore.VTable = .{ .create = cStoreCreateZ, .list = cStoreListZ, .freeSessionInfos = cStoreFreeInfos, .resolve = cStoreResolveZ, .latest = cStoreLatestZ, .load = cStoreLoad, .appendMessages = cStoreAppend };

fn builtinStoreCreate(ctx: *anyopaque, out: **PantoSession) callconv(.c) PantoStatus {
    return wrapBuiltinSession(@as(*panto.SessionStore, @ptrCast(@alignCast(ctx))).create(), out);
}
fn builtinStoreList(ctx: *anyopaque, out: *PantoSessionInfoList) callconv(.c) PantoStatus {
    const s: *panto.SessionStore = @ptrCast(@alignCast(ctx));
    const infos = s.list() catch |e| return setErr("{t}", .{e});
    defer s.freeSessionInfos(infos);
    const c_infos = allocator.alloc(PantoSessionInfo, infos.len) catch return setErr("OutOfMemory", .{});
    for (infos, 0..) |info, i| c_infos[i] = marshalSessionInfo(info) catch return setErr("OutOfMemory", .{});
    out.* = .{ .ptr = c_infos.ptr, .len = c_infos.len };
    return .ok;
}
fn builtinStoreFreeInfos(_: *anyopaque, infos: PantoSessionInfoList) callconv(.c) void {
    panto_session_info_list_destroy(infos);
}
fn builtinStoreResolve(ctx: *anyopaque, id: PantoSlice, out: *PantoSessionResult) callconv(.c) PantoStatus {
    const s: *panto.SessionStore = @ptrCast(@alignCast(ctx));
    if (s.resolve(slice(id)) catch |e| return setErr("{t}", .{e})) |sess| return wrapBuiltinResult(sess, out);
    out.* = .{ .found = false, .session = null };
    return .ok;
}
fn builtinStoreLatest(ctx: *anyopaque, out: *PantoSessionResult) callconv(.c) PantoStatus {
    const s: *panto.SessionStore = @ptrCast(@alignCast(ctx));
    if (s.latest() catch |e| return setErr("{t}", .{e})) |sess| return wrapBuiltinResult(sess, out);
    out.* = .{ .found = false, .session = null };
    return .ok;
}
fn builtinStoreLoad(ctx: *anyopaque, id: PantoSlice, out: **PantoConversation) callconv(.c) PantoStatus {
    const s: *panto.SessionStore = @ptrCast(@alignCast(ctx));
    const conv = s.load(slice(id)) catch |e| return setErr("{t}", .{e});
    if (conv == null) return setErr("NotFound", .{});
    const ch = allocator.create(ConversationHandle) catch return setErr("OutOfMemory", .{});
    ch.* = .{ .conversation = conv.? };
    out.* = @ptrCast(ch);
    return .ok;
}
fn builtinStoreAppend(ctx: *anyopaque, session_id: PantoSlice, messages: [*]const PantoPersistentMessage, len: usize) callconv(.c) PantoStatus {
    const s: *panto.SessionStore = @ptrCast(@alignCast(ctx));
    const pmsgs = allocator.alloc(panto.PersistentMessage, len) catch return setErr("OutOfMemory", .{});
    defer allocator.free(pmsgs);
    for (messages[0..len], 0..) |m, i| pmsgs[i] = .{ .message = .{ .role = @enumFromInt(@intFromEnum(m.role)), .content = .empty, .metadata = if (m.has_metadata) slice(m.metadata) else null }, .usage = if (m.has_usage) zigUsage(m.usage) else null, .identity = .{ .api_style = .openai_chat, .base_url = "", .model = "" } };
    s.appendMessages(slice(session_id), pmsgs) catch |e| return setErr("{t}", .{e});
    return .ok;
}
fn wrapBuiltinSession(sess: panto.Session, out: **PantoSession) PantoStatus {
    out.* = wrapSession(sess, true) catch |e| return setErr("{t}", .{e});
    return .ok;
}
fn wrapBuiltinResult(sess: panto.Session, out: *PantoSessionResult) PantoStatus {
    var ps: *PantoSession = undefined;
    const st = wrapBuiltinSession(sess, &ps);
    if (st != .ok) return st;
    out.* = .{ .found = true, .session = ps };
    return .ok;
}
fn nullStoreDestroy(ctx: *anyopaque) callconv(.c) void {
    const s: *panto.NullStore = @ptrCast(@alignCast(ctx));
    const h: *NullStoreHandle = @fieldParentPtr("store", s);
    allocator.destroy(h);
}
fn fsJSONLStoreDestroy(ctx: *anyopaque) callconv(.c) void {
    const s: *panto.FileSystemJSONLStore = @ptrCast(@alignCast(ctx));
    const h: *FileSystemJSONLStoreHandle = @fieldParentPtr("store", s);
    h.store.deinit();
    allocator.destroy(h);
}

const null_store_vtable: PantoSessionStoreVTable = .{ .create = builtinStoreCreate, .list = builtinStoreList, .free_session_infos = builtinStoreFreeInfos, .resolve = builtinStoreResolve, .latest = builtinStoreLatest, .load = builtinStoreLoad, .append_messages = builtinStoreAppend, .destroy = nullStoreDestroy };
const fs_jsonl_store_vtable: PantoSessionStoreVTable = .{ .create = builtinStoreCreate, .list = builtinStoreList, .free_session_infos = builtinStoreFreeInfos, .resolve = builtinStoreResolve, .latest = builtinStoreLatest, .load = builtinStoreLoad, .append_messages = builtinStoreAppend, .destroy = fsJSONLStoreDestroy };

export fn panto_agent_create(c: *const PantoConfig, s: ?*PantoSession, conv: ?*PantoConversation, out: **PantoAgent) PantoStatus {
    const cfg = convertConfig(c) catch |e| return setErr("{t}", .{e});
    const sess = if (s) |sp| blk: {
        const sh: *SessionHandle = @ptrCast(@alignCast(sp));
        sh.owns_info = false;
        break :blk sh.session;
    } else blk: {
        var ns = panto.NullStore.init(allocator);
        break :blk ns.store().create();
    };
    var maybe_conv: ?panto.Conversation = null;
    if (conv) |cp| {
        const ch: *ConversationHandle = @ptrCast(@alignCast(cp));
        maybe_conv = ch.conversation;
        ch.conversation = panto.Conversation.init(allocator);
    }
    const a = panto.Agent.init(allocator, threaded.?.io(), cfg, sess, maybe_conv) catch |e| {
        freeConfig(cfg);
        return setErr("{t}", .{e});
    };
    const h = allocator.create(AgentHandle) catch return setErr("OutOfMemory", .{});
    h.* = .{ .agent = a, .config = cfg };
    out.* = @ptrCast(h);
    return .ok;
}
export fn panto_agent_destroy(a: ?*PantoAgent) void {
    if (a) |ptr| {
        const h: *AgentHandle = @ptrCast(@alignCast(ptr));
        h.agent.deinit();
        freeConfig(h.config);
        allocator.destroy(h);
    }
}
export fn panto_agent_session_id(a: *PantoAgent) PantoSlice {
    const h: *AgentHandle = @ptrCast(@alignCast(a));
    return outSlice(h.agent.sessionId());
}
export fn panto_agent_conversation(a: *PantoAgent) *PantoConversation {
    const h: *AgentHandle = @ptrCast(@alignCast(a));
    return @ptrCast(&h.agent.conversation);
}
export fn panto_agent_set_config(a: *PantoAgent, c: *const PantoConfig) PantoStatus {
    const h: *AgentHandle = @ptrCast(@alignCast(a));
    const cfg = convertConfig(c) catch |e| return setErr("{t}", .{e});
    const old = h.config;
    h.config = cfg;
    h.agent.setConfig(cfg);
    freeConfig(old);
    return .ok;
}
export fn panto_agent_add_system_message(a: *PantoAgent, text: ?[*:0]const u8) PantoStatus {
    const h: *AgentHandle = @ptrCast(@alignCast(a));
    h.agent.addSystemMessage(cstr(text)) catch |e| return setErr("{t}", .{e});
    return .ok;
}
export fn panto_agent_set_system_prompt(a: *PantoAgent, text: ?[*:0]const u8) PantoStatus {
    const h: *AgentHandle = @ptrCast(@alignCast(a));
    h.agent.setSystemPrompt(cstr(text)) catch |e| return setErr("{t}", .{e});
    return .ok;
}
export fn panto_agent_compact(a: *PantoAgent, override_system_prompt: ?[*:0]const u8, extra_instructions: ?[*:0]const u8, out: *PantoCompactionResult) PantoStatus {
    const h: *AgentHandle = @ptrCast(@alignCast(a));
    const osp = if (override_system_prompt == null or cstr(override_system_prompt).len == 0) null else cstr(override_system_prompt);
    const extra = if (extra_instructions == null or cstr(extra_instructions).len == 0) null else cstr(extra_instructions);
    const r = h.agent.compact(osp, extra) catch |e| return setErr("{t}", .{e});
    out.* = .{ .compacted = r.compacted, .kept_turns = r.kept_turns, .summarized_messages = r.summarized_messages };
    return .ok;
}
export fn panto_agent_run(a: *PantoAgent, text: ?[*:0]const u8, out: **PantoStream) PantoStatus {
    const h: *AgentHandle = @ptrCast(@alignCast(a));
    const st = h.agent.run(.{ .text = cstr(text) }) catch |e| return setErr("{t}", .{e});
    out.* = @ptrCast(st);
    return .ok;
}
export fn panto_stream_reopen(s: *PantoStream) PantoStatus {
    const st: *panto.Stream = @ptrCast(@alignCast(s));
    st.reopen() catch |e| return setErr("{t}", .{e});
    return .ok;
}
export fn panto_stream_destroy(s: ?*PantoStream) void {
    if (s) |ptr| {
        const st: *panto.Stream = @ptrCast(@alignCast(ptr));
        st.deinit();
    }
}
export fn panto_stream_next(s: *PantoStream, out: *PantoEvent) PantoNextStatus {
    const st: *panto.Stream = @ptrCast(@alignCast(s));
    const ev = st.next() catch |e| return setErrNext("{t}", .{e});
    if (ev) |e| {
        out.* = marshalEvent(e) catch |err| return setErrNext("{t}", .{err});
        return .event;
    }
    return .done;
}
export fn panto_event_free(ev: *PantoEvent) void {
    switch (ev.tag) {
        .tool_details => {
            freePS(ev.data.tool_details.id);
            freePS(ev.data.tool_details.name);
        },
        .content_delta => freePS(ev.data.content_delta.delta),
        .provider_retry => {
            freePS(ev.data.provider_retry.error_name);
            freePS(ev.data.provider_retry.message);
        },
        else => {},
    }
    ev.* = undefined;
}
fn freePS(s: PantoSlice) void {
    if (s.ptr) |p| allocator.free(@constCast(p[0..s.len]));
}

fn marshalEvent(ev: panto.Event) !PantoEvent {
    return switch (ev) {
        .message_start => |r| .{ .tag = .message_start, .data = .{ .message_start = @enumFromInt(@intFromEnum(r)) } },
        .block_start => |b| .{ .tag = .block_start, .data = .{ .block_start = .{ .block_type = @enumFromInt(@intFromEnum(b.block_type)), .index = b.index } } },
        .tool_details => |t| .{ .tag = .tool_details, .data = .{ .tool_details = .{ .index = t.index, .id = try dupOut(t.id), .name = try dupOut(t.name) } } },
        .content_delta => |d| .{ .tag = .content_delta, .data = .{ .content_delta = .{ .index = d.index, .delta = try dupOut(d.delta) } } },
        .block_complete => |b| .{ .tag = .block_complete, .data = .{ .block_complete = .{ .index = b.index, .block_type = @enumFromInt(@intFromEnum(b.block)) } } },
        .message_complete => |m| .{ .tag = .message_complete, .data = .{ .message_complete = .{ .has_usage = m.usage != null, .usage = if (m.usage) |u| usage(u) else .{ .input = 0, .output = 0, .cache_read = 0, .cache_write = 0, .reasoning = 0 } } } },
        .provider_retry => |r| .{ .tag = .provider_retry, .data = .{ .provider_retry = .{ .attempt = r.attempt, .max_attempts = r.max_attempts, .delay_ms = r.delay_ms, .error_name = try dupOut(@errorName(r.err)), .has_status_code = r.status_code != null, .status_code = r.status_code orelse 0, .has_retry_after_ms = r.retry_after_ms != null, .retry_after_ms = r.retry_after_ms orelse 0, .message = try dupOut(r.message orelse ""), .compaction = r.compaction } } },
        .tool_dispatch_start => |t| .{ .tag = .tool_dispatch_start, .data = .{ .tool_dispatch_start = .{ .count = t.count } } },
        .tool_dispatch_complete => .{ .tag = .tool_dispatch_complete, .data = .{ .tool_dispatch_complete = .{ .message_index = 0 } } },
        .turn_complete => .{ .tag = .turn_complete, .data = undefined },
    };
}
fn usage(u: panto.Usage) PantoUsage {
    return .{ .input = u.input, .output = u.output, .cache_read = u.cache_read, .cache_write = u.cache_write, .reasoning = u.reasoning };
}
fn zigUsage(u: PantoUsage) panto.Usage {
    return .{ .input = u.input, .output = u.output, .cache_read = u.cache_read, .cache_write = u.cache_write, .reasoning = u.reasoning };
}

test "c abi exports compile" {
    try std.testing.expect(true);
}

fn cloneToolDecl(d: PantoToolDecl) !panto.ToolDecl {
    return .{ .name = try dupSlice(d.name), .description = try dupSlice(d.description), .schema_json = try dupSlice(d.schema_json) };
}
fn freeToolDecl(d: panto.ToolDecl) void {
    allocator.free(d.name);
    allocator.free(d.description);
    allocator.free(d.schema_json);
}
fn toolInvoke(ctx: *anyopaque, input: []const u8, alloc: std.mem.Allocator) anyerror!panto.ResultParts {
    _ = alloc;
    const h: *ToolHandle = @ptrCast(@alignCast(ctx));
    var out: PantoResultParts = .{ .ptr = null, .len = 0 };
    if (h.invoke(h.ctx, outSlice(input), &out) != .ok) return error.ToolCallbackFailed;
    return convertResultParts(out);
}
fn toolDeinit(ctx: *anyopaque, alloc: std.mem.Allocator) void {
    _ = alloc;
    const h: *ToolHandle = @ptrCast(@alignCast(ctx));
    if (h.destroy) |d| d(h.ctx);
    freeToolDecl(h.decl);
    allocator.destroy(h);
}
fn sourceInvokeBatch(ctx: *anyopaque, calls: []const panto.ToolCall, results: []panto.ToolCallResult, alloc: std.mem.Allocator) anyerror!void {
    _ = alloc;
    const h: *ToolSourceHandle = @ptrCast(@alignCast(ctx));
    const ccalls = try allocator.alloc(PantoToolCall, calls.len);
    defer allocator.free(ccalls);
    const cresults = try allocator.alloc(PantoToolCallResult, results.len);
    defer allocator.free(cresults);
    for (calls, 0..) |c, i| ccalls[i] = .{ .tool_name = outSlice(c.tool_name), .input = outSlice(c.input) };
    for (cresults) |*r| r.* = .{ .ok = false, .parts = .{ .ptr = null, .len = 0 }, .err = .{ .ptr = null, .len = 0 } };
    if (h.invoke_batch(h.ctx, ccalls.ptr, cresults.ptr, cresults.len) != .ok) return error.ToolSourceCallbackFailed;
    for (cresults, 0..) |r, i| {
        if (r.ok) results[i] = .{ .ok = try convertResultParts(r.parts) } else results[i] = .{ .err = error.ToolCallbackFailed };
    }
}
fn sourceDeinit(ctx: *anyopaque, alloc: std.mem.Allocator) void {
    _ = alloc;
    const h: *ToolSourceHandle = @ptrCast(@alignCast(ctx));
    if (h.destroy) |d| d(h.ctx);
    allocator.free(h.name);
    for (h.decls) |d| freeToolDecl(d);
    allocator.free(h.decls);
    allocator.destroy(h);
}
fn convertResultParts(parts: PantoResultParts) !panto.ResultParts {
    const out = try allocator.alloc(panto.ResultPart, parts.len);
    errdefer allocator.free(out);
    if (parts.ptr) |p| {
        for (p[0..parts.len], 0..) |part, i| {
            out[i] = switch (part.tag) {
                .text => .{ .text = try dupSlice(part.data.text) },
                .media => .{ .media = .{ .media_type = if (part.data.media.has_media_type) try dupSlice(part.data.media.media_type) else null, .data = try dupSlice(part.data.media.data) } },
            };
        }
    }
    return .{ .items = out };
}
export fn panto_agent_register_tool(a: *PantoAgent, decl: PantoToolDecl, ctx: *anyopaque, invoke: PantoToolInvokeFn, destroy: ?PantoToolDestroyFn) PantoStatus {
    const ah: *AgentHandle = @ptrCast(@alignCast(a));
    const h = allocator.create(ToolHandle) catch return setErr("OutOfMemory", .{});
    h.* = .{ .ctx = ctx, .invoke = invoke, .destroy = destroy, .decl = cloneToolDecl(decl) catch |e| { allocator.destroy(h); return setErr("{t}", .{e}); } };
    ah.agent.registerTool(.{ .decl = h.decl, .ctx = h, .vtable = &.{ .invoke = toolInvoke, .deinit = toolDeinit } }) catch |e| return setErr("{t}", .{e});
    return .ok;
}
export fn panto_agent_register_tool_source(a: *PantoAgent, name: PantoSlice, decls: [*]const PantoToolDecl, len: usize, ctx: *anyopaque, invoke_batch: PantoToolSourceInvokeBatchFn, destroy: ?PantoToolDestroyFn) PantoStatus {
    const ah: *AgentHandle = @ptrCast(@alignCast(a));
    const h = allocator.create(ToolSourceHandle) catch return setErr("OutOfMemory", .{});
    h.name = dupSlice(name) catch |e| { allocator.destroy(h); return setErr("{t}", .{e}); };
    h.decls = allocator.alloc(panto.ToolDecl, len) catch |e| { allocator.free(h.name); allocator.destroy(h); return setErr("{t}", .{e}); };
    for (decls[0..len], 0..) |d, i| h.decls[i] = cloneToolDecl(d) catch |e| return setErr("{t}", .{e});
    h.ctx = ctx; h.invoke_batch = invoke_batch; h.destroy = destroy;
    ah.agent.registerToolSource(.{ .name = h.name, .tools = h.decls, .ctx = h, .vtable = &.{ .invoke_batch = sourceInvokeBatch, .deinit = sourceDeinit } }) catch |e| return setErr("{t}", .{e});
    return .ok;
}
export fn panto_result_parts_text(text: ?[*:0]const u8) PantoResultParts {
    const part = allocator.alloc(PantoResultPart, 1) catch return .{ .ptr = null, .len = 0 };
    part[0] = .{ .tag = .text, .data = .{ .text = dupOut(cstr(text)) catch .{ .ptr = null, .len = 0 } } };
    return .{ .ptr = part.ptr, .len = 1 };
}
export fn panto_result_parts_destroy(parts: PantoResultParts) void {
    if (parts.ptr) |p| {
        for (p[0..parts.len]) |part| switch (part.tag) {
            .text => freePS(part.data.text),
            .media => { if (part.data.media.has_media_type) freePS(part.data.media.media_type); freePS(part.data.media.data); },
        };
        allocator.free(p[0..parts.len]);
    }
}