package panto

/*
#cgo CFLAGS: -I../libpanto-c/include
#cgo LDFLAGS: -L../libpanto-c/zig-out/lib -lpanto
#include <panto.h>
#include <stdlib.h>
extern PantoStatus pantoGoStoreCreate(void *ctx, PantoSession **out);
extern PantoStatus pantoGoStoreList(void *ctx, PantoSessionInfoList *out);
extern void pantoGoStoreFreeSessionInfos(void *ctx, PantoSessionInfoList infos);
extern PantoStatus pantoGoStoreResolve(void *ctx, PantoSlice id, PantoSessionResult *out);
extern PantoStatus pantoGoStoreLatest(void *ctx, PantoSessionResult *out);
extern PantoStatus pantoGoStoreLoad(void *ctx, PantoSlice id, PantoConversation **out);
extern PantoStatus pantoGoStoreAppendMessages(void *ctx, PantoSlice session_id, PantoPersistentMessage *messages, size_t len);
static PantoStatus pantoGoStoreAppendMessagesConst(void *ctx, PantoSlice session_id, const PantoPersistentMessage *messages, size_t len) {
  return pantoGoStoreAppendMessages(ctx, session_id, (PantoPersistentMessage*)messages, len);
}
extern PantoStatus pantoGoToolInvoke(void *ctx, PantoSlice input, PantoResultParts *out);
extern PantoStatus pantoGoToolSourceInvokeBatch(void *ctx, PantoToolCall *calls, PantoToolCallResult *results, size_t len);
extern void pantoGoCallbackDestroy(void *ctx);
static PantoSessionStoreVTable panto_go_store_vtable = {
  pantoGoStoreCreate,
  pantoGoStoreList,
  pantoGoStoreFreeSessionInfos,
  pantoGoStoreResolve,
  pantoGoStoreLatest,
  pantoGoStoreLoad,
  pantoGoStoreAppendMessagesConst,
  pantoGoCallbackDestroy,
};
static PantoStatus panto_go_session_store_create(void *ctx, PantoSessionStore **out) {
  return panto_session_store_create(ctx, &panto_go_store_vtable, out);
}
*/
import "C"

import (
	"errors"
	"fmt"
	"iter"
	"runtime"
	"unsafe"
)

type (
	APIStyle        int
	ReasoningEffort int
	Thinking        int
	Effort          int
	MessageRole     int
	ContentBlockTag int
	EventTag        int
	SystemMode      int
)

const (
	OpenAIChat APIStyle = iota
	AnthropicMessages
)

const (
	ReasoningDefault ReasoningEffort = iota
	ReasoningOff
	ReasoningMinimal
	ReasoningLow
	ReasoningMedium
	ReasoningHigh
)

const (
	ThinkingDisabled Thinking = iota
	ThinkingEnabled
	ThinkingAdaptive
)

const (
	EffortLow Effort = iota
	EffortMedium
	EffortHigh
	EffortXHigh
	EffortMax
)

const (
	RoleSystem MessageRole = iota
	RoleUser
	RoleAssistant
)

const (
	BlockText ContentBlockTag = iota
	BlockThinking
	BlockToolUse
	BlockToolResult
	BlockSystem
	BlockCompactionSummary
)

const (
	SystemAppend SystemMode = iota
	SystemReplace
)

const (
	EventMessageStart EventTag = iota
	EventBlockStart
	EventToolDetails
	EventContentDelta
	EventBlockComplete
	EventMessageComplete
	EventProviderRetry
	EventToolDispatchStart
	EventToolDispatchComplete
	EventTurnComplete
)

type Config struct {
	Provider   ProviderConfig
	Compaction CompactionConfig
	Retry      RetryConfig
}
type ProviderConfig struct {
	OpenAIChat        *OpenAIChatConfig
	AnthropicMessages *AnthropicMessagesConfig
}
type OpenAIChatConfig struct {
	APIKey, BaseURL, Model string
	Reasoning              ReasoningEffort
	MaxTokens              uint32
}
type AnthropicMessagesConfig struct {
	APIKey, BaseURL, Model, APIVersion string
	MaxTokens                          uint32
	Thinking                           Thinking
	Effort                             Effort
	ThinkingBudgetTokens               *uint32
	ThinkingInterleaved                bool
}
type CompactionConfig struct {
	KeepVerbatim     uint32
	Model            *ProviderConfig
	CompactionPrompt *string
}
type RetryConfig struct {
	MaxAttempts                uint
	InitialDelayMS, MaxDelayMS uint64
	Multiplier                 float64
	Jitter                     bool
}
type (
	Usage            struct{ Input, Output, CacheRead, CacheWrite, Reasoning uint64 }
	CompactionResult struct {
		Compacted                     bool
		KeptTurns, SummarizedMessages uint
	}
)

type Event struct {
	Tag                  EventTag
	MessageStart         MessageRole
	BlockStart           BlockStart
	ToolDetails          ToolDetails
	ContentDelta         ContentDelta
	BlockComplete        BlockComplete
	MessageComplete      MessageComplete
	ProviderRetry        ProviderRetry
	ToolDispatchStart    ToolDispatchStart
	ToolDispatchComplete ToolDispatchComplete
}
type BlockStart struct {
	BlockType ContentBlockTag
	Index     uint
}
type ToolDetails struct {
	Index    uint
	ID, Name string
}
type ContentDelta struct {
	Index uint
	Delta string
}
type BlockComplete struct {
	Index     uint
	BlockType ContentBlockTag
}
type (
	MessageComplete struct{ Usage *Usage }
	ProviderRetry   struct {
		Attempt, MaxAttempts uint
		DelayMS              uint64
		ErrorName            string
		StatusCode           *uint16
		RetryAfterMS         *uint64
		Message              string
		Compaction           bool
	}
)

type (
	ToolDispatchStart    struct{ Count uint }
	ToolDispatchComplete struct{ MessageIndex uint }
)

type (
	Agent  struct{ ptr *C.PantoAgent }
	Stream struct {
		ptr  *C.PantoStream
		err  error
		done bool
	}
)

type Conversation struct {
	ptr   *C.PantoConversation
	owned bool
}
type (
	Session     struct{ ptr *C.PantoSession }
	SessionInfo struct {
		ID, Created, Modified, LastUserMessage, BaseURL, Model string
		MessageCount                                           uint
		APIStyle                                               APIStyle
		Reasoning                                              ReasoningEffort
	}
)

type SessionStore interface {
	Create() (*Session, error)
	List() ([]SessionInfo, error)
	Resolve(id string) (*Session, bool, error)
	Latest() (*Session, bool, error)
	Load(id string) (*Conversation, bool, error)
	AppendMessages(sessionID string, messages []PersistentMessage) error
}
type (
	cSessionStore        interface{ cptr() *C.PantoSessionStore }
	NullStore            struct{ ptr *C.PantoSessionStore }
	FileSystemJSONLStore struct{ ptr *C.PantoSessionStore }
	GoSessionStore       struct {
		ptr  *C.PantoSessionStore
		impl SessionStore
	}
)

type PersistentMessage struct {
	Role     MessageRole
	Usage    *Usage
	Metadata string
	Content  []OwnedContentBlock
}
type OwnedMessage struct {
	Role     MessageRole
	Usage    *Usage
	Metadata string
	Content  []OwnedContentBlock
}
type OwnedContentBlock struct {
	Tag        ContentBlockTag
	Text       string
	ToolID     string
	ToolName   string
	IsError    bool
	SystemMode SystemMode
}

type cStrings []*C.char

func (cs cStrings) free() {
	for _, s := range cs {
		C.free(unsafe.Pointer(s))
	}
}
func Init()   { C.panto_init() }
func Deinit() { C.panto_deinit() }
func lastError() error {
	s := C.panto_last_error()
	if s.ptr == nil || s.len == 0 {
		return errors.New("libpanto error")
	}
	return errors.New(C.GoStringN((*C.char)(unsafe.Pointer(s.ptr)), C.int(s.len)))
}

func NewNullStore() (*NullStore, error) {
	var out *C.PantoSessionStore
	if C.panto_null_store_create(&out) != C.PANTO_OK {
		return nil, lastError()
	}
	s := &NullStore{out}
	runtime.SetFinalizer(s, (*NullStore).Close)
	return s, nil
}
func (s *NullStore) cptr() *C.PantoSessionStore                { return s.ptr }
func (s *NullStore) Create() (*Session, error)                 { return CreateSession(s) }
func (s *NullStore) List() ([]SessionInfo, error)              { return ListSessions(s) }
func (s *NullStore) Resolve(id string) (*Session, bool, error) { return ResolveSession(s, id) }
func (s *NullStore) Latest() (*Session, bool, error)           { return LatestSession(s) }
func (s *NullStore) Load(id string) (*Conversation, bool, error) {
	sess, ok, err := ResolveSession(s, id)
	if err != nil || !ok {
		return nil, ok, err
	}
	c, err := sess.Load()
	return c, err == nil, err
}
func (s *NullStore) AppendMessages(sessionID string, messages []PersistentMessage) error { return nil }
func (s *NullStore) Close() {
	if s != nil && s.ptr != nil {
		C.panto_session_store_destroy(s.ptr)
		s.ptr = nil
	}
}

func NewFileSystemJSONLStore(dir, metadata string) (*FileSystemJSONLStore, error) {
	cd := C.CString(dir)
	defer C.free(unsafe.Pointer(cd))
	cm := C.CString(metadata)
	defer C.free(unsafe.Pointer(cm))
	var out *C.PantoSessionStore
	if C.panto_file_system_jsonl_store_create(cd, cm, &out) != C.PANTO_OK {
		return nil, lastError()
	}
	s := &FileSystemJSONLStore{out}
	runtime.SetFinalizer(s, (*FileSystemJSONLStore).Close)
	return s, nil
}
func (s *FileSystemJSONLStore) cptr() *C.PantoSessionStore   { return s.ptr }
func (s *FileSystemJSONLStore) Create() (*Session, error)    { return CreateSession(s) }
func (s *FileSystemJSONLStore) List() ([]SessionInfo, error) { return ListSessions(s) }
func (s *FileSystemJSONLStore) Resolve(id string) (*Session, bool, error) {
	return ResolveSession(s, id)
}
func (s *FileSystemJSONLStore) Latest() (*Session, bool, error) { return LatestSession(s) }
func (s *FileSystemJSONLStore) Load(id string) (*Conversation, bool, error) {
	sess, ok, err := ResolveSession(s, id)
	if err != nil || !ok {
		return nil, ok, err
	}
	c, err := sess.Load()
	return c, err == nil, err
}

func (s *FileSystemJSONLStore) AppendMessages(sessionID string, messages []PersistentMessage) error {
	return nil
}

func (s *FileSystemJSONLStore) Close() {
	if s != nil && s.ptr != nil {
		C.panto_session_store_destroy(s.ptr)
		s.ptr = nil
	}
}

func CreateSession(store cSessionStore) (*Session, error) {
	var out *C.PantoSession
	if C.panto_session_store_create_session(store.cptr(), &out) != C.PANTO_OK {
		return nil, lastError()
	}
	s := &Session{out}
	runtime.SetFinalizer(s, (*Session).Close)
	return s, nil
}

func ResolveSession(store cSessionStore, id string) (*Session, bool, error) {
	cid := C.CString(id)
	defer C.free(unsafe.Pointer(cid))
	var r C.PantoSessionResult
	if C.panto_session_store_resolve(store.cptr(), cid, &r) != C.PANTO_OK {
		return nil, false, lastError()
	}
	if !bool(r.found) {
		return nil, false, nil
	}
	s := &Session{r.session}
	runtime.SetFinalizer(s, (*Session).Close)
	return s, true, nil
}

func LatestSession(store cSessionStore) (*Session, bool, error) {
	var r C.PantoSessionResult
	if C.panto_session_store_latest(store.cptr(), &r) != C.PANTO_OK {
		return nil, false, lastError()
	}
	if !bool(r.found) {
		return nil, false, nil
	}
	s := &Session{r.session}
	runtime.SetFinalizer(s, (*Session).Close)
	return s, true, nil
}

func ListSessions(store cSessionStore) ([]SessionInfo, error) {
	var l C.PantoSessionInfoList
	if C.panto_session_store_list(store.cptr(), &l) != C.PANTO_OK {
		return nil, lastError()
	}
	defer C.panto_session_info_list_destroy(l)
	out := make([]SessionInfo, int(l.len))
	if l.ptr != nil {
		xs := unsafe.Slice(l.ptr, int(l.len))
		for i, x := range xs {
			out[i] = sessionInfo(x)
		}
	}
	return out, nil
}

func (s *Session) Close() {
	if s != nil && s.ptr != nil {
		C.panto_session_destroy(s.ptr)
		s.ptr = nil
	}
}

func (s *Session) Load() (*Conversation, error) {
	var out *C.PantoConversation
	if C.panto_session_load(s.ptr, &out) != C.PANTO_OK {
		return nil, lastError()
	}
	c := &Conversation{ptr: out, owned: true}
	runtime.SetFinalizer(c, (*Conversation).Close)
	return c, nil
}

func NewConversation() (*Conversation, error) {
	var out *C.PantoConversation
	if C.panto_conversation_create(&out) != C.PANTO_OK {
		return nil, lastError()
	}
	c := &Conversation{ptr: out, owned: true}
	runtime.SetFinalizer(c, (*Conversation).Close)
	return c, nil
}

func (c *Conversation) Close() {
	if c != nil && c.owned && c.ptr != nil {
		C.panto_conversation_destroy(c.ptr)
		c.ptr = nil
	}
}
func (c *Conversation) MessageCount() uint     { return uint(C.panto_conversation_message_count(c.ptr)) }
func (c *Conversation) Message(i uint) Message { return Message{conv: c, index: i} }
func (c *Conversation) AddSystemMessage(text string) error {
	ct := C.CString(text)
	defer C.free(unsafe.Pointer(ct))
	if C.panto_conversation_add_system_message(c.ptr, ct) != C.PANTO_OK {
		return lastError()
	}
	return nil
}

func (c *Conversation) ReplaceSystemMessage(text string) error {
	ct := C.CString(text)
	defer C.free(unsafe.Pointer(ct))
	if C.panto_conversation_replace_system_message(c.ptr, ct) != C.PANTO_OK {
		return lastError()
	}
	return nil
}

func (c *Conversation) AddUserText(text string) error {
	ct := C.CString(text)
	defer C.free(unsafe.Pointer(ct))
	if C.panto_conversation_add_user_text(c.ptr, ct) != C.PANTO_OK {
		return lastError()
	}
	return nil
}

func (c *Conversation) AddAssistantText(text string, u *Usage) error {
	ct := C.CString(text)
	defer C.free(unsafe.Pointer(ct))
	var cu C.PantoUsage
	has := false
	if u != nil {
		cu = cUsage(*u)
		has = true
	}
	if C.panto_conversation_add_assistant_text(c.ptr, ct, C.bool(has), cu) != C.PANTO_OK {
		return lastError()
	}
	return nil
}

func (c *Conversation) AddCompactionSummary(text string) error {
	ct := C.CString(text)
	defer C.free(unsafe.Pointer(ct))
	if C.panto_conversation_add_compaction_summary(c.ptr, ct) != C.PANTO_OK {
		return lastError()
	}
	return nil
}

type Message struct {
	conv  *Conversation
	index uint
}

func (m Message) Role() MessageRole {
	return MessageRole(C.panto_conversation_message_role(m.conv.ptr, C.size_t(m.index)))
}

func (m Message) Usage() *Usage {
	if !bool(C.panto_conversation_message_has_usage(m.conv.ptr, C.size_t(m.index))) {
		return nil
	}
	u := usage(C.panto_conversation_message_usage(m.conv.ptr, C.size_t(m.index)))
	return &u
}

func (m Message) BlockCount() uint {
	return uint(C.panto_conversation_message_block_count(m.conv.ptr, C.size_t(m.index)))
}

func (m Message) Block(i uint) ContentBlock {
	return ContentBlock{conv: m.conv, msg: m.index, index: i}
}

func (m Message) Snapshot() OwnedMessage {
	blocks := make([]OwnedContentBlock, m.BlockCount())
	for i := range blocks {
		blocks[i] = m.Block(uint(i)).Snapshot()
	}
	return OwnedMessage{Role: m.Role(), Usage: m.Usage(), Content: blocks}
}

type ContentBlock struct {
	conv       *Conversation
	msg, index uint
}

func (b ContentBlock) Tag() ContentBlockTag {
	return ContentBlockTag(C.panto_conversation_block_tag(b.conv.ptr, C.size_t(b.msg), C.size_t(b.index)))
}

func (b ContentBlock) Text() string {
	return goSlice(C.panto_conversation_block_text(b.conv.ptr, C.size_t(b.msg), C.size_t(b.index)))
}

func (b ContentBlock) ToolID() string {
	return goSlice(C.panto_conversation_block_tool_id(b.conv.ptr, C.size_t(b.msg), C.size_t(b.index)))
}

func (b ContentBlock) ToolName() string {
	return goSlice(C.panto_conversation_block_tool_name(b.conv.ptr, C.size_t(b.msg), C.size_t(b.index)))
}

func (b ContentBlock) ToolResultIsError() bool {
	return bool(C.panto_conversation_block_tool_result_is_error(b.conv.ptr, C.size_t(b.msg), C.size_t(b.index)))
}

func (b ContentBlock) SystemMode() SystemMode {
	return SystemMode(C.panto_conversation_block_system_mode(b.conv.ptr, C.size_t(b.msg), C.size_t(b.index)))
}

func (b ContentBlock) Snapshot() OwnedContentBlock {
	return OwnedContentBlock{
		Tag:        b.Tag(),
		Text:       b.Text(),
		ToolID:     b.ToolID(),
		ToolName:   b.ToolName(),
		IsError:    b.ToolResultIsError(),
		SystemMode: b.SystemMode(),
	}
}

func NewAgent(cfg Config) (*Agent, error) {
	st, err := NewNullStore()
	if err != nil {
		return nil, err
	}
	sess, err := CreateSession(st)
	st.Close()
	if err != nil {
		return nil, err
	}
	return NewAgentWithSession(cfg, sess, nil)
}

func NewAgentWithSession(cfg Config, session *Session, conv *Conversation) (*Agent, error) {
	ccfg, strings, err := cfg.c()
	if err != nil {
		return nil, err
	}
	defer strings.free()
	var cconv *C.PantoConversation
	if conv != nil {
		cconv = conv.ptr
		conv.owned = false
		runtime.SetFinalizer(conv, nil)
	}
	var out *C.PantoAgent
	if C.panto_agent_create(&ccfg, session.ptr, cconv, &out) != C.PANTO_OK {
		return nil, lastError()
	}
	a := &Agent{out}
	runtime.SetFinalizer(a, (*Agent).Close)
	return a, nil
}

func (a *Agent) Close() {
	if a != nil && a.ptr != nil {
		C.panto_agent_destroy(a.ptr)
		a.ptr = nil
	}
}
func (a *Agent) SessionID() string { return goSlice(C.panto_agent_session_id(a.ptr)) }
func (a *Agent) Conversation() *Conversation {
	return &Conversation{ptr: C.panto_agent_conversation(a.ptr), owned: false}
}

func (a *Agent) SetConfig(cfg Config) error {
	ccfg, strings, err := cfg.c()
	if err != nil {
		return err
	}
	defer strings.free()
	if C.panto_agent_set_config(a.ptr, &ccfg) != C.PANTO_OK {
		return lastError()
	}
	return nil
}

func (a *Agent) Compact(overrideSystemPrompt, extraInstructions *string) (CompactionResult, error) {
	var co, ce *C.char
	if overrideSystemPrompt != nil {
		co = C.CString(*overrideSystemPrompt)
		defer C.free(unsafe.Pointer(co))
	}
	if extraInstructions != nil {
		ce = C.CString(*extraInstructions)
		defer C.free(unsafe.Pointer(ce))
	}
	var out C.PantoCompactionResult
	if C.panto_agent_compact(a.ptr, co, ce, &out) != C.PANTO_OK {
		return CompactionResult{}, lastError()
	}
	return CompactionResult{
		Compacted:          bool(out.compacted),
		KeptTurns:          uint(out.kept_turns),
		SummarizedMessages: uint(out.summarized_messages),
	}, nil
}

func (a *Agent) Run(userText string) (*Stream, error) {
	ct := C.CString(userText)
	defer C.free(unsafe.Pointer(ct))
	var out *C.PantoStream
	if C.panto_agent_run(a.ptr, ct, &out) != C.PANTO_OK {
		return nil, lastError()
	}
	s := &Stream{ptr: out}
	runtime.SetFinalizer(s, (*Stream).Close)
	return s, nil
}

func (a *Agent) AddSystemMessage(text string) error {
	ct := C.CString(text)
	defer C.free(unsafe.Pointer(ct))
	if C.panto_agent_add_system_message(a.ptr, ct) != C.PANTO_OK {
		return lastError()
	}
	return nil
}

func (a *Agent) SetSystemPrompt(text string) error {
	ct := C.CString(text)
	defer C.free(unsafe.Pointer(ct))
	if C.panto_agent_set_system_prompt(a.ptr, ct) != C.PANTO_OK {
		return lastError()
	}
	return nil
}

func (s *Stream) Close() {
	if s != nil && s.ptr != nil {
		C.panto_stream_destroy(s.ptr)
		s.ptr = nil
	}
}

func (s *Stream) Next() (Event, bool, error) {
	if s.err != nil {
		return Event{}, false, s.err
	}
	if s.done {
		return Event{}, false, nil
	}
	var cev C.PantoEvent
	status := C.panto_stream_next(s.ptr, &cev)
	switch status {
	case C.PANTO_NEXT_EVENT:
		defer C.panto_event_free(&cev)
		ev := marshalEvent(&cev)
		if ev.Tag == EventTurnComplete {
			s.done = true
		}
		return ev, true, nil
	case C.PANTO_NEXT_DONE:
		s.done = true
		return Event{}, false, nil
	case C.PANTO_NEXT_ERROR:
		s.err = lastError()
		return Event{}, false, s.err
	default:
		s.err = fmt.Errorf("unknown panto next status %d", int(status))
		return Event{}, false, s.err
	}
}
func (s *Stream) Err() error { return s.err }
func (s *Stream) Iter() iter.Seq[Event] {
	return func(yield func(Event) bool) {
		for {
			ev, ok, err := s.Next()
			if err != nil || !ok {
				return
			}
			if !yield(ev) {
				return
			}
			if ev.Tag == EventTurnComplete {
				return
			}
		}
	}
}

func (s *Stream) Chan() <-chan Event {
	ch := make(chan Event)
	go func() {
		defer close(ch)
		for ev := range s.Iter() {
			ch <- ev
		}
	}()
	return ch
}

func (cfg Config) c() (C.PantoConfig, cStrings, error) {
	var cs cStrings
	provider, pstrings, err := cfg.Provider.c()
	cs = append(cs, pstrings...)
	if err != nil {
		cs.free()
		return C.PantoConfig{}, nil, err
	}
	out := C.PantoConfig{provider: provider}
	out.compaction.keep_verbatim = C.uint32_t(cfg.Compaction.KeepVerbatim)
	if cfg.Compaction.Model != nil {
		m, ms, err := cfg.Compaction.Model.c()
		cs = append(cs, ms...)
		if err != nil {
			cs.free()
			return C.PantoConfig{}, nil, err
		}
		out.compaction.has_model = true
		out.compaction.model = m
	}
	if cfg.Compaction.CompactionPrompt != nil {
		c := C.CString(*cfg.Compaction.CompactionPrompt)
		cs = append(cs, c)
		out.compaction.has_compaction_prompt = true
		out.compaction.compaction_prompt = c
	}
	out.retry.max_attempts = C.size_t(cfg.Retry.MaxAttempts)
	out.retry.initial_delay_ms = C.uint64_t(cfg.Retry.InitialDelayMS)
	out.retry.max_delay_ms = C.uint64_t(cfg.Retry.MaxDelayMS)
	out.retry.multiplier = C.double(cfg.Retry.Multiplier)
	out.retry.jitter = C.bool(cfg.Retry.Jitter)
	return out, cs, nil
}

func (p ProviderConfig) c() (C.PantoProviderConfig, cStrings, error) {
	var out C.PantoProviderConfig
	var cs cStrings
	if p.OpenAIChat != nil == (p.AnthropicMessages != nil) {
		return out, nil, errors.New("exactly one provider config must be set")
	}
	if p.OpenAIChat != nil {
		out.tag = C.PANTO_OPENAI_CHAT
		setOpenAI(&out, p.OpenAIChat, &cs)
		return out, cs, nil
	}
	out.tag = C.PANTO_ANTHROPIC_MESSAGES
	setAnthropic(&out, p.AnthropicMessages, &cs)
	return out, cs, nil
}

func setOpenAI(out *C.PantoProviderConfig, cfg *OpenAIChatConfig, cs *cStrings) {
	apiKey, baseURL, model := C.CString(cfg.APIKey), C.CString(cfg.BaseURL), C.CString(cfg.Model)
	*cs = append(*cs, apiKey, baseURL, model)
	c := (*C.PantoOpenAIChatConfig)(unsafe.Pointer(&out.data[0]))
	c.api_key = apiKey
	c.base_url = baseURL
	c.model = model
	c.reasoning = C.PantoReasoningEffort(cfg.Reasoning)
	c.max_tokens = C.uint32_t(cfg.MaxTokens)
}

func setAnthropic(out *C.PantoProviderConfig, cfg *AnthropicMessagesConfig, cs *cStrings) {
	apiKey, baseURL, model, ver := C.CString(cfg.APIKey), C.CString(cfg.BaseURL), C.CString(cfg.Model), C.CString(cfg.APIVersion)
	*cs = append(*cs, apiKey, baseURL, model, ver)
	c := (*C.PantoAnthropicMessagesConfig)(unsafe.Pointer(&out.data[0]))
	c.api_key = apiKey
	c.base_url = baseURL
	c.model = model
	c.api_version = ver
	c.max_tokens = C.uint32_t(cfg.MaxTokens)
	c.thinking = C.PantoThinking(cfg.Thinking)
	c.effort = C.PantoEffort(cfg.Effort)
	c.thinking_interleaved = C.bool(cfg.ThinkingInterleaved)
	if cfg.ThinkingBudgetTokens != nil {
		c.has_thinking_budget_tokens = true
		c.thinking_budget_tokens = C.uint32_t(*cfg.ThinkingBudgetTokens)
	}
}

func marshalEvent(cev *C.PantoEvent) Event {
	ev := Event{Tag: EventTag(cev.tag)}
	switch cev.tag {
	case C.PANTO_EVENT_MESSAGE_START:
		ev.MessageStart = MessageRole(*(*C.PantoMessageRole)(unsafe.Pointer(&cev.data[0])))
	case C.PANTO_EVENT_BLOCK_START:
		b := (*C.PantoBlockStart)(unsafe.Pointer(&cev.data[0]))
		ev.BlockStart = BlockStart{BlockType: ContentBlockTag(b.block_type), Index: uint(b.index)}
	case C.PANTO_EVENT_TOOL_DETAILS:
		t := (*C.PantoToolDetails)(unsafe.Pointer(&cev.data[0]))
		ev.ToolDetails = ToolDetails{Index: uint(t.index), ID: goSlice(t.id), Name: goSlice(t.name)}
	case C.PANTO_EVENT_CONTENT_DELTA:
		d := (*C.PantoContentDelta)(unsafe.Pointer(&cev.data[0]))
		ev.ContentDelta = ContentDelta{Index: uint(d.index), Delta: goSlice(d.delta)}
	case C.PANTO_EVENT_BLOCK_COMPLETE:
		b := (*C.PantoBlockComplete)(unsafe.Pointer(&cev.data[0]))
		ev.BlockComplete = BlockComplete{Index: uint(b.index), BlockType: ContentBlockTag(b.block_type)}
	case C.PANTO_EVENT_MESSAGE_COMPLETE:
		m := (*C.PantoMessageComplete)(unsafe.Pointer(&cev.data[0]))
		if m.has_usage {
			u := usage(m.usage)
			ev.MessageComplete.Usage = &u
		}
	case C.PANTO_EVENT_PROVIDER_RETRY:
		r := (*C.PantoProviderRetry)(unsafe.Pointer(&cev.data[0]))
		ev.ProviderRetry = ProviderRetry{
			Attempt:     uint(r.attempt),
			MaxAttempts: uint(r.max_attempts),
			DelayMS:     uint64(r.delay_ms),
			ErrorName:   goSlice(r.error_name),
			Message:     goSlice(r.message),
			Compaction:  bool(r.compaction),
		}
		if r.has_status_code {
			v := uint16(r.status_code)
			ev.ProviderRetry.StatusCode = &v
		}
		if r.has_retry_after_ms {
			v := uint64(r.retry_after_ms)
			ev.ProviderRetry.RetryAfterMS = &v
		}
	case C.PANTO_EVENT_TOOL_DISPATCH_START:
		t := (*C.PantoToolDispatchStart)(unsafe.Pointer(&cev.data[0]))
		ev.ToolDispatchStart = ToolDispatchStart{Count: uint(t.count)}
	case C.PANTO_EVENT_TOOL_DISPATCH_COMPLETE:
		t := (*C.PantoToolDispatchComplete)(unsafe.Pointer(&cev.data[0]))
		ev.ToolDispatchComplete = ToolDispatchComplete{MessageIndex: uint(t.message_index)}
	}
	return ev
}

func goSlice(s C.PantoSlice) string {
	if s.ptr == nil || s.len == 0 {
		return ""
	}
	return C.GoStringN((*C.char)(unsafe.Pointer(s.ptr)), C.int(s.len))
}

func usage(u C.PantoUsage) Usage {
	return Usage{
		Input:      uint64(u.input),
		Output:     uint64(u.output),
		CacheRead:  uint64(u.cache_read),
		CacheWrite: uint64(u.cache_write),
		Reasoning:  uint64(u.reasoning),
	}
}

func cUsage(u Usage) C.PantoUsage {
	return C.PantoUsage{
		input:       C.uint64_t(u.Input),
		output:      C.uint64_t(u.Output),
		cache_read:  C.uint64_t(u.CacheRead),
		cache_write: C.uint64_t(u.CacheWrite),
		reasoning:   C.uint64_t(u.Reasoning),
	}
}

func sessionInfo(i C.PantoSessionInfo) SessionInfo {
	return SessionInfo{
		ID:              goSlice(i.id),
		Created:         goSlice(i.created),
		Modified:        goSlice(i.modified),
		LastUserMessage: goSlice(i.last_user_message),
		BaseURL:         goSlice(i.base_url),
		Model:           goSlice(i.model),
		MessageCount:    uint(i.message_count),
		APIStyle:        APIStyle(i.api_style),
		Reasoning:       ReasoningEffort(i.reasoning),
	}
}

// Tool callback support.
type (
	ToolDecl    struct{ Name, Description, SchemaJSON string }
	ResultPart  struct{ Text string }
	ResultParts []ResultPart
	ToolFunc    func(input string) (ResultParts, error)
	Tool        struct {
		Decl   ToolDecl
		Invoke ToolFunc
	}
)

type (
	ToolCall       struct{ ToolName, Input string }
	ToolSourceFunc func(calls []ToolCall) ([]ResultParts, []error, error)
	ToolSource     struct {
		Name        string
		Tools       []ToolDecl
		InvokeBatch ToolSourceFunc
	}
)

var (
	callbackHandles            = map[uintptr]any{}
	nextCallbackHandle uintptr = 1
)

func saveCallback(v any) unsafe.Pointer {
	h := nextCallbackHandle
	nextCallbackHandle++
	callbackHandles[h] = v
	return unsafe.Pointer(h)
}
func dropCallback(p unsafe.Pointer) { delete(callbackHandles, uintptr(p)) }

//export pantoGoToolInvoke
func pantoGoToolInvoke(ctx unsafe.Pointer, input C.PantoSlice, out *C.PantoResultParts) C.PantoStatus {
	t := callbackHandles[uintptr(ctx)].(Tool)
	parts, err := t.Invoke(goSlice(input))
	if err != nil {
		return C.PANTO_ERROR
	}
	*out = makeCResultParts(parts)
	return C.PANTO_OK
}

//export pantoGoToolSourceInvokeBatch
func pantoGoToolSourceInvokeBatch(ctx unsafe.Pointer, calls *C.PantoToolCall, results *C.PantoToolCallResult, n C.size_t) C.PantoStatus {
	src := callbackHandles[uintptr(ctx)].(ToolSource)
	cc := unsafe.Slice(calls, int(n))
	goCalls := make([]ToolCall, int(n))
	for i, c := range cc {
		goCalls[i] = ToolCall{ToolName: goSlice(c.tool_name), Input: goSlice(c.input)}
	}
	parts, errs, err := src.InvokeBatch(goCalls)
	if err != nil {
		return C.PANTO_ERROR
	}
	rr := unsafe.Slice(results, int(n))
	for i := range rr {
		if i < len(errs) && errs[i] != nil {
			rr[i].ok = false
			continue
		}
		rr[i].ok = true
		if i < len(parts) {
			rr[i].parts = makeCResultParts(parts[i])
		}
	}
	return C.PANTO_OK
}

//export pantoGoCallbackDestroy
func pantoGoCallbackDestroy(ctx unsafe.Pointer) { dropCallback(ctx) }

func (a *Agent) RegisterTool(t Tool) error {
	ctx := saveCallback(t)
	d, free := cToolDecl(t.Decl)
	defer free()
	if C.panto_agent_register_tool(a.ptr, d, ctx, (C.PantoToolInvokeFn)(C.pantoGoToolInvoke), (C.PantoToolDestroyFn)(C.pantoGoCallbackDestroy)) != C.PANTO_OK {
		dropCallback(ctx)
		return lastError()
	}
	return nil
}

func (a *Agent) RegisterToolSource(src ToolSource) error {
	ctx := saveCallback(src)
	cname := cSlice(src.Name)
	defer C.free(unsafe.Pointer(cname.ptr))
	decls := make([]C.PantoToolDecl, len(src.Tools))
	frees := make([]func(), 0, len(src.Tools))
	for i, d := range src.Tools {
		cd, fr := cToolDecl(d)
		decls[i] = cd
		frees = append(frees, fr)
	}
	defer func() {
		for _, f := range frees {
			f()
		}
	}()
	var ptr *C.PantoToolDecl
	if len(decls) > 0 {
		ptr = &decls[0]
	}
	if C.panto_agent_register_tool_source(a.ptr, cname, ptr, C.size_t(len(decls)), ctx, (C.PantoToolSourceInvokeBatchFn)(C.pantoGoToolSourceInvokeBatch), (C.PantoToolDestroyFn)(C.pantoGoCallbackDestroy)) != C.PANTO_OK {
		dropCallback(ctx)
		return lastError()
	}
	return nil
}

func cToolDecl(d ToolDecl) (C.PantoToolDecl, func()) {
	n := cSlice(d.Name)
	desc := cSlice(d.Description)
	schema := cSlice(d.SchemaJSON)
	return C.PantoToolDecl{name: n, description: desc, schema_json: schema}, func() {
		C.free(unsafe.Pointer(n.ptr))
		C.free(unsafe.Pointer(desc.ptr))
		C.free(unsafe.Pointer(schema.ptr))
	}
}

func cSlice(s string) C.PantoSlice {
	cs := C.CString(s)
	return C.PantoSlice{ptr: (*C.uint8_t)(unsafe.Pointer(cs)), len: C.size_t(len(s))}
}

func makeCResultParts(parts ResultParts) C.PantoResultParts {
	if len(parts) == 0 {
		return C.PantoResultParts{}
	}
	arr := (*C.PantoResultPart)(C.calloc(C.size_t(len(parts)), C.size_t(unsafe.Sizeof(C.PantoResultPart{}))))
	xs := unsafe.Slice(arr, len(parts))
	for i, p := range parts {
		cs := cSlice(p.Text)
		xs[i].tag = C.PANTO_RESULT_TEXT
		(*C.PantoSlice)(unsafe.Pointer(&xs[i].data[0])).ptr = cs.ptr
		(*C.PantoSlice)(unsafe.Pointer(&xs[i].data[0])).len = cs.len
	}
	return C.PantoResultParts{ptr: arr, len: C.size_t(len(parts))}
}

func NewGoSessionStore(impl SessionStore) (*GoSessionStore, error) {
	ctx := saveCallback(impl)
	var out *C.PantoSessionStore
	if C.panto_go_session_store_create(ctx, &out) != C.PANTO_OK {
		dropCallback(ctx)
		return nil, lastError()
	}
	s := &GoSessionStore{ptr: out, impl: impl}
	runtime.SetFinalizer(s, (*GoSessionStore).Close)
	return s, nil
}
func (s *GoSessionStore) cptr() *C.PantoSessionStore                  { return s.ptr }
func (s *GoSessionStore) Create() (*Session, error)                   { return CreateSession(s) }
func (s *GoSessionStore) List() ([]SessionInfo, error)                { return ListSessions(s) }
func (s *GoSessionStore) Resolve(id string) (*Session, bool, error)   { return ResolveSession(s, id) }
func (s *GoSessionStore) Latest() (*Session, bool, error)             { return LatestSession(s) }
func (s *GoSessionStore) Load(id string) (*Conversation, bool, error) { return s.impl.Load(id) }
func (s *GoSessionStore) AppendMessages(sessionID string, messages []PersistentMessage) error {
	return s.impl.AppendMessages(sessionID, messages)
}

func (s *GoSessionStore) Close() {
	if s != nil && s.ptr != nil {
		C.panto_session_store_destroy(s.ptr)
		s.ptr = nil
	}
}

//export pantoGoStoreCreate
func pantoGoStoreCreate(ctx unsafe.Pointer, out **C.PantoSession) C.PantoStatus {
	impl := callbackHandles[uintptr(ctx)].(SessionStore)
	s, err := impl.Create()
	if err != nil {
		return C.PANTO_ERROR
	}
	*out = s.ptr
	runtime.SetFinalizer(s, nil)
	return C.PANTO_OK
}

//export pantoGoStoreList
func pantoGoStoreList(ctx unsafe.Pointer, out *C.PantoSessionInfoList) C.PantoStatus {
	impl := callbackHandles[uintptr(ctx)].(SessionStore)
	infos, err := impl.List()
	if err != nil {
		return C.PANTO_ERROR
	}
	if len(infos) == 0 {
		*out = C.PantoSessionInfoList{}
		return C.PANTO_OK
	}
	arr := (*C.PantoSessionInfo)(C.calloc(C.size_t(len(infos)), C.size_t(unsafe.Sizeof(C.PantoSessionInfo{}))))
	xs := unsafe.Slice(arr, len(infos))
	for i, info := range infos {
		xs[i] = cSessionInfo(info)
	}
	*out = C.PantoSessionInfoList{ptr: arr, len: C.size_t(len(infos))}
	return C.PANTO_OK
}

//export pantoGoStoreFreeSessionInfos
func pantoGoStoreFreeSessionInfos(ctx unsafe.Pointer, infos C.PantoSessionInfoList) {
	_ = ctx
	freeCSessionInfoList(infos)
}

//export pantoGoStoreResolve
func pantoGoStoreResolve(ctx unsafe.Pointer, id C.PantoSlice, out *C.PantoSessionResult) C.PantoStatus {
	impl := callbackHandles[uintptr(ctx)].(SessionStore)
	s, ok, err := impl.Resolve(goSlice(id))
	if err != nil {
		return C.PANTO_ERROR
	}
	if !ok {
		*out = C.PantoSessionResult{}
		return C.PANTO_OK
	}
	*out = C.PantoSessionResult{found: true, session: s.ptr}
	runtime.SetFinalizer(s, nil)
	return C.PANTO_OK
}

//export pantoGoStoreLatest
func pantoGoStoreLatest(ctx unsafe.Pointer, out *C.PantoSessionResult) C.PantoStatus {
	impl := callbackHandles[uintptr(ctx)].(SessionStore)
	s, ok, err := impl.Latest()
	if err != nil {
		return C.PANTO_ERROR
	}
	if !ok {
		*out = C.PantoSessionResult{}
		return C.PANTO_OK
	}
	*out = C.PantoSessionResult{found: true, session: s.ptr}
	runtime.SetFinalizer(s, nil)
	return C.PANTO_OK
}

//export pantoGoStoreLoad
func pantoGoStoreLoad(ctx unsafe.Pointer, id C.PantoSlice, out **C.PantoConversation) C.PantoStatus {
	impl := callbackHandles[uintptr(ctx)].(SessionStore)
	c, ok, err := impl.Load(goSlice(id))
	if err != nil {
		return C.PANTO_ERROR
	}
	if !ok {
		return C.PANTO_ERROR
	}
	*out = c.ptr
	c.owned = false
	runtime.SetFinalizer(c, nil)
	return C.PANTO_OK
}

//export pantoGoStoreAppendMessages
func pantoGoStoreAppendMessages(ctx unsafe.Pointer, sessionID C.PantoSlice, messages *C.PantoPersistentMessage, n C.size_t) C.PantoStatus {
	impl := callbackHandles[uintptr(ctx)].(SessionStore)
	xs := unsafe.Slice(messages, int(n))
	out := make([]PersistentMessage, int(n))
	for i, m := range xs {
		var u *Usage
		if m.has_usage {
			uu := usage(m.usage)
			u = &uu
		}
		out[i] = PersistentMessage{Role: MessageRole(m.role), Usage: u, Metadata: goSlice(m.metadata)}
	}
	if err := impl.AppendMessages(goSlice(sessionID), out); err != nil {
		return C.PANTO_ERROR
	}
	return C.PANTO_OK
}

func cSessionInfo(i SessionInfo) C.PantoSessionInfo {
	return C.PantoSessionInfo{
		id:                cSlice(i.ID),
		created:           cSlice(i.Created),
		modified:          cSlice(i.Modified),
		last_user_message: cSlice(i.LastUserMessage),
		base_url:          cSlice(i.BaseURL),
		model:             cSlice(i.Model),
		message_count:     C.size_t(i.MessageCount),
		api_style:         C.PantoAPIStyle(i.APIStyle),
		reasoning:         C.PantoReasoningEffort(i.Reasoning),
	}
}

func freeCSessionInfoList(l C.PantoSessionInfoList) {
	if l.ptr == nil {
		return
	}
	xs := unsafe.Slice(l.ptr, int(l.len))
	for _, i := range xs {
		C.free(unsafe.Pointer(i.id.ptr))
		C.free(unsafe.Pointer(i.created.ptr))
		C.free(unsafe.Pointer(i.modified.ptr))
		C.free(unsafe.Pointer(i.last_user_message.ptr))
		C.free(unsafe.Pointer(i.base_url.ptr))
		C.free(unsafe.Pointer(i.model.ptr))
	}
	C.free(unsafe.Pointer(l.ptr))
}