#ifndef PANTO_H
#define PANTO_H

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

#ifdef __cplusplus
extern "C" {
#endif

#if defined(_WIN32)
#define PANTO_EXPORT __declspec(dllexport)
#else
#define PANTO_EXPORT __attribute__((visibility("default")))
#endif

typedef struct PantoAgent PantoAgent;
typedef struct PantoStream PantoStream;
typedef struct PantoConversation PantoConversation;
typedef struct PantoSession PantoSession;
typedef struct PantoSessionStore PantoSessionStore;

typedef struct { const uint8_t *ptr; size_t len; } PantoSlice;

typedef enum { PANTO_OK = 0, PANTO_ERROR = 1 } PantoStatus;
typedef enum { PANTO_NEXT_EVENT = 0, PANTO_NEXT_DONE = 1, PANTO_NEXT_ERROR = 2 } PantoNextStatus;
typedef enum { PANTO_OPENAI_CHAT = 0, PANTO_ANTHROPIC_MESSAGES = 1 } PantoAPIStyle;
typedef enum { PANTO_REASONING_DEFAULT = 0, PANTO_REASONING_OFF, PANTO_REASONING_MINIMAL, PANTO_REASONING_LOW, PANTO_REASONING_MEDIUM, PANTO_REASONING_HIGH } PantoReasoningEffort;
typedef enum { PANTO_THINKING_DISABLED = 0, PANTO_THINKING_ENABLED, PANTO_THINKING_ADAPTIVE } PantoThinking;
typedef enum { PANTO_EFFORT_LOW = 0, PANTO_EFFORT_MEDIUM, PANTO_EFFORT_HIGH, PANTO_EFFORT_XHIGH, PANTO_EFFORT_MAX } PantoEffort;
typedef enum { PANTO_ROLE_SYSTEM = 0, PANTO_ROLE_USER, PANTO_ROLE_ASSISTANT } PantoMessageRole;
typedef enum { PANTO_BLOCK_TEXT = 0, PANTO_BLOCK_THINKING, PANTO_BLOCK_TOOL_USE, PANTO_BLOCK_TOOL_RESULT, PANTO_BLOCK_SYSTEM, PANTO_BLOCK_COMPACTION_SUMMARY } PantoContentBlockTag;
typedef enum { PANTO_SYSTEM_APPEND = 0, PANTO_SYSTEM_REPLACE } PantoSystemMode;
typedef enum { PANTO_EVENT_MESSAGE_START = 0, PANTO_EVENT_BLOCK_START, PANTO_EVENT_TOOL_DETAILS, PANTO_EVENT_CONTENT_DELTA, PANTO_EVENT_BLOCK_COMPLETE, PANTO_EVENT_MESSAGE_COMPLETE, PANTO_EVENT_PROVIDER_RETRY, PANTO_EVENT_TOOL_DISPATCH_START, PANTO_EVENT_TOOL_DISPATCH_COMPLETE, PANTO_EVENT_TURN_COMPLETE } PantoEventTag;

typedef struct { uint64_t input, output, cache_read, cache_write, reasoning; } PantoUsage;
typedef struct { PantoAPIStyle api_style; PantoSlice base_url; PantoSlice model; PantoReasoningEffort reasoning; PantoThinking thinking; PantoEffort effort; bool has_thinking_budget_tokens; uint32_t thinking_budget_tokens; bool thinking_interleaved; } PantoWireIdentity;
typedef struct { PantoSlice id, created, modified, last_user_message, base_url, model; size_t message_count; PantoAPIStyle api_style; PantoReasoningEffort reasoning; } PantoSessionInfo;
typedef struct { PantoSessionInfo *ptr; size_t len; } PantoSessionInfoList;
typedef struct { bool found; PantoSession *session; } PantoSessionResult;
typedef struct { const char *api_key, *base_url, *model; PantoReasoningEffort reasoning; uint32_t max_tokens; } PantoOpenAIChatConfig;
typedef struct { const char *api_key, *base_url, *model, *api_version; uint32_t max_tokens; PantoThinking thinking; PantoEffort effort; bool has_thinking_budget_tokens; uint32_t thinking_budget_tokens; bool thinking_interleaved; } PantoAnthropicMessagesConfig;
typedef struct { PantoAPIStyle tag; union { PantoOpenAIChatConfig openai_chat; PantoAnthropicMessagesConfig anthropic_messages; } data; } PantoProviderConfig;
typedef struct { uint32_t keep_verbatim; bool has_model; PantoProviderConfig model; bool has_compaction_prompt; const char *compaction_prompt; } PantoCompactionConfig;
typedef struct { size_t max_attempts; uint64_t initial_delay_ms, max_delay_ms; double multiplier; bool jitter; } PantoRetryConfig;
typedef struct { PantoProviderConfig provider; PantoCompactionConfig compaction; PantoRetryConfig retry; } PantoConfig;

typedef struct { PantoContentBlockTag block_type; size_t index; } PantoBlockStart;
typedef struct { size_t index; PantoSlice id, name; } PantoToolDetails;
typedef struct { size_t index; PantoSlice delta; } PantoContentDelta;
typedef struct { size_t index; PantoContentBlockTag block_type; } PantoBlockComplete;
typedef struct { bool has_usage; PantoUsage usage; } PantoMessageComplete;
typedef struct { bool compacted; size_t kept_turns; size_t summarized_messages; } PantoCompactionResult;
typedef struct { size_t attempt, max_attempts; uint64_t delay_ms; PantoSlice error_name; bool has_status_code; uint16_t status_code; bool has_retry_after_ms; uint64_t retry_after_ms; PantoSlice message; bool compaction; } PantoProviderRetry;
typedef struct { size_t count; } PantoToolDispatchStart;
typedef struct { size_t message_index; } PantoToolDispatchComplete;

typedef struct { PantoEventTag tag; union { PantoMessageRole message_start; PantoBlockStart block_start; PantoToolDetails tool_details; PantoContentDelta content_delta; PantoBlockComplete block_complete; PantoMessageComplete message_complete; PantoProviderRetry provider_retry; PantoToolDispatchStart tool_dispatch_start; PantoToolDispatchComplete tool_dispatch_complete; } data; } PantoEvent;

/* One content block of a message being appended. A flattened, borrow-only
 * view: every slice points into the in-memory message and is valid only for
 * the duration of the append_messages call. `text` carries the Text body,
 * Thinking text, ToolUse input JSON, concatenated ToolResult text, or
 * System/CompactionSummary text depending on `tag`. `tool_id` is the ToolUse
 * id or ToolResult tool_use_id; `tool_name` is the ToolUse name; `is_error`
 * is the ToolResult error flag; `system_mode` is the System block mode;
 * `thinking_signature` is the Thinking signature (empty when absent), and the
 * `thinking_signature_*` fields record the provider/style/model that emitted
 * it. To replay a thinking block faithfully (Anthropic drops thinking blocks
 * whose signature lacks a matching origin) a store must persist the signature
 * AND all three origin fields, then feed them back via the message builder. */
typedef struct {
  PantoContentBlockTag tag;
  PantoSlice text;
  PantoSlice tool_id;
  PantoSlice tool_name;
  bool is_error;
  PantoSystemMode system_mode;
  PantoSlice thinking_signature;
  PantoAPIStyle thinking_signature_api_style;
  PantoSlice thinking_signature_base_url;
  PantoSlice thinking_signature_model;
} PantoOwnedContentBlock;

/* `api_style`/`base_url`/`model`/`reasoning` are the per-message wire identity
 * (the provider that produced this message), which can drift within a single
 * conversation (compaction on a different model, a mid-chat model switch). A
 * store should persist these per message rather than from static config. */
typedef struct { PantoMessageRole role; bool has_usage; PantoUsage usage; bool has_metadata; PantoSlice metadata; PantoAPIStyle api_style; PantoSlice base_url; PantoSlice model; PantoReasoningEffort reasoning; const PantoOwnedContentBlock *content; size_t content_len; } PantoPersistentMessage;

typedef struct {
  PantoStatus (*create)(void *ctx, PantoSession **out);
  PantoStatus (*list)(void *ctx, PantoSessionInfoList *out);
  void (*free_session_infos)(void *ctx, PantoSessionInfoList infos);
  PantoStatus (*resolve)(void *ctx, PantoSlice id, PantoSessionResult *out);
  PantoStatus (*latest)(void *ctx, PantoSessionResult *out);
  PantoStatus (*load)(void *ctx, PantoSlice id, PantoConversation **out);
  PantoStatus (*append_messages)(void *ctx, PantoSlice session_id, const PantoPersistentMessage *messages, size_t len);
  void (*destroy)(void *ctx);
} PantoSessionStoreVTable;

PANTO_EXPORT void panto_init(void);
PANTO_EXPORT void panto_deinit(void);
PANTO_EXPORT PantoSlice panto_last_error(void);
PANTO_EXPORT void panto_error_free(PantoSlice s);
PANTO_EXPORT PantoStatus panto_conversation_create(PantoConversation **out);
PANTO_EXPORT void panto_conversation_destroy(PantoConversation *conversation);
PANTO_EXPORT size_t panto_conversation_message_count(PantoConversation *conversation);
PANTO_EXPORT PantoMessageRole panto_conversation_message_role(PantoConversation *conversation, size_t index);
PANTO_EXPORT bool panto_conversation_message_has_usage(PantoConversation *conversation, size_t index);
PANTO_EXPORT PantoUsage panto_conversation_message_usage(PantoConversation *conversation, size_t index);
PANTO_EXPORT size_t panto_conversation_message_block_count(PantoConversation *conversation, size_t message_index);
PANTO_EXPORT PantoContentBlockTag panto_conversation_block_tag(PantoConversation *conversation, size_t message_index, size_t block_index);
PANTO_EXPORT PantoSlice panto_conversation_block_text(PantoConversation *conversation, size_t message_index, size_t block_index);
PANTO_EXPORT PantoSlice panto_conversation_block_tool_id(PantoConversation *conversation, size_t message_index, size_t block_index);
PANTO_EXPORT PantoSlice panto_conversation_block_tool_name(PantoConversation *conversation, size_t message_index, size_t block_index);
PANTO_EXPORT bool panto_conversation_block_tool_result_is_error(PantoConversation *conversation, size_t message_index, size_t block_index);
PANTO_EXPORT PantoSystemMode panto_conversation_block_system_mode(PantoConversation *conversation, size_t message_index, size_t block_index);
PANTO_EXPORT PantoStatus panto_conversation_add_system_message(PantoConversation *conversation, const char *text);
PANTO_EXPORT PantoStatus panto_conversation_replace_system_message(PantoConversation *conversation, const char *text);
PANTO_EXPORT PantoStatus panto_conversation_add_user_text(PantoConversation *conversation, const char *text);
PANTO_EXPORT PantoStatus panto_conversation_add_assistant_text(PantoConversation *conversation, const char *text, bool has_usage, PantoUsage usage);
PANTO_EXPORT PantoStatus panto_conversation_add_compaction_summary(PantoConversation *conversation, const char *text);

/* Rich, block-level message builder. Accumulate content blocks, then commit
 * the whole message to a conversation in one call — the path for rebuilding a
 * persisted conversation that contains tool calls or thinking. The builder
 * uses the same allocator as the conversation it is committed to.
 *
 * Usage: create -> add_* (one per block, in order) -> conversation_add_message.
 * `panto_conversation_add_message` ALWAYS consumes the builder (it is freed on
 * both success and failure); do not destroy it afterwards. Call
 * `panto_message_builder_destroy` only to discard a builder you never commit.
 * Each `text`/`signature`/etc. argument is copied. */
typedef struct PantoMessageBuilder PantoMessageBuilder;
PANTO_EXPORT PantoMessageBuilder *panto_message_builder_create(PantoMessageRole role);
PANTO_EXPORT void panto_message_builder_destroy(PantoMessageBuilder *builder);
PANTO_EXPORT PantoStatus panto_message_builder_add_text(PantoMessageBuilder *builder, const char *text);
/* `signature` may be NULL/empty when the provider emitted no signature, in
 * which case the `signature_*` origin args are ignored. When a signature is
 * supplied, pass the origin (style/base_url/model) it was produced under so
 * the block can be replayed; an Anthropic request drops thinking blocks whose
 * signature origin does not match the request's base_url/model. */
PANTO_EXPORT PantoStatus panto_message_builder_add_thinking(PantoMessageBuilder *builder, const char *text, const char *signature, PantoAPIStyle signature_api_style, const char *signature_base_url, const char *signature_model);
PANTO_EXPORT PantoStatus panto_message_builder_add_tool_use(PantoMessageBuilder *builder, const char *id, const char *name, const char *input);
PANTO_EXPORT PantoStatus panto_message_builder_add_tool_result(PantoMessageBuilder *builder, const char *tool_use_id, const char *text, bool is_error);
PANTO_EXPORT PantoStatus panto_message_builder_add_system(PantoMessageBuilder *builder, const char *text, PantoSystemMode mode);
/* Commit the builder's blocks as one message of the builder's role. Consumes
 * (frees) the builder. `usage` applies to assistant turns; pass has_usage=false
 * otherwise. */
PANTO_EXPORT PantoStatus panto_conversation_add_message(PantoConversation *conversation, PantoMessageBuilder *builder, bool has_usage, PantoUsage usage);
PANTO_EXPORT PantoStatus panto_session_create_null(PantoSession **out);
PANTO_EXPORT PantoStatus panto_session_create(PantoSessionStore *store, PantoSessionInfo info, PantoSession **out);
PANTO_EXPORT void panto_session_destroy(PantoSession *session);
PANTO_EXPORT PantoStatus panto_session_store_create(void *ctx, const PantoSessionStoreVTable *vtable, PantoSessionStore **out);
PANTO_EXPORT void panto_session_store_destroy(PantoSessionStore *store);
PANTO_EXPORT PantoStatus panto_null_store_create(PantoSessionStore **out);
PANTO_EXPORT PantoStatus panto_file_system_jsonl_store_create(const char *dir, const char *metadata, PantoSessionStore **out);
PANTO_EXPORT PantoStatus panto_session_store_create_session(PantoSessionStore *store, PantoSession **out);
PANTO_EXPORT PantoStatus panto_session_store_list(PantoSessionStore *store, PantoSessionInfoList *out);
PANTO_EXPORT void panto_session_info_list_destroy(PantoSessionInfoList infos);
PANTO_EXPORT PantoStatus panto_session_store_resolve(PantoSessionStore *store, const char *id, PantoSessionResult *out);
PANTO_EXPORT PantoStatus panto_session_store_latest(PantoSessionStore *store, PantoSessionResult *out);
PANTO_EXPORT PantoStatus panto_session_load(PantoSession *session, PantoConversation **out);
PANTO_EXPORT PantoStatus panto_agent_create(const PantoConfig *config, PantoSession *session, PantoConversation *conversation, PantoAgent **out);
PANTO_EXPORT PantoConversation *panto_agent_conversation(PantoAgent *agent);
PANTO_EXPORT void panto_agent_destroy(PantoAgent *agent);
PANTO_EXPORT PantoSlice panto_agent_session_id(PantoAgent *agent);
PANTO_EXPORT PantoStatus panto_agent_set_config(PantoAgent *agent, const PantoConfig *config);
PANTO_EXPORT PantoStatus panto_agent_add_system_message(PantoAgent *agent, const char *text);
PANTO_EXPORT PantoStatus panto_agent_set_system_prompt(PantoAgent *agent, const char *text);
PANTO_EXPORT PantoStatus panto_agent_compact(PantoAgent *agent, const char *override_system_prompt, const char *extra_instructions, PantoCompactionResult *out);
PANTO_EXPORT PantoStatus panto_agent_run(PantoAgent *agent, const char *user_text, PantoStream **out);
/* Reset a failed stream back to its turn-open boundary so the caller can
 * resume panto_stream_next() after changing the agent config (e.g. catch a
 * terminal bad-request, swap the provider config, and retry the SAME turn
 * without re-appending the user message). Errors if the stream has not
 * failed. */
PANTO_EXPORT PantoStatus panto_stream_reopen(PantoStream *stream);
PANTO_EXPORT void panto_stream_destroy(PantoStream *stream);
PANTO_EXPORT PantoNextStatus panto_stream_next(PantoStream *stream, PantoEvent *out);
PANTO_EXPORT void panto_event_free(PantoEvent *event);

/* Go/callback-oriented tool ABI. */
typedef struct { PantoSlice name, description, schema_json; } PantoToolDecl;
typedef struct { PantoSlice media_type; bool has_media_type; PantoSlice data; } PantoMediaPart;
typedef enum { PANTO_RESULT_TEXT = 0, PANTO_RESULT_MEDIA = 1 } PantoResultPartTag;
typedef struct { PantoResultPartTag tag; union { PantoSlice text; PantoMediaPart media; } data; } PantoResultPart;
typedef struct { PantoResultPart *ptr; size_t len; } PantoResultParts;
typedef struct { PantoSlice tool_name, input; } PantoToolCall;
typedef struct { bool ok; PantoResultParts parts; PantoSlice error; } PantoToolCallResult;
typedef PantoStatus (*PantoToolInvokeFn)(void *ctx, PantoSlice input, PantoResultParts *out);
typedef PantoStatus (*PantoToolSourceInvokeBatchFn)(void *ctx, const PantoToolCall *calls, PantoToolCallResult *results, size_t len);
typedef void (*PantoToolDestroyFn)(void *ctx);
PANTO_EXPORT PantoStatus panto_agent_register_tool(PantoAgent *agent, PantoToolDecl decl, void *ctx, PantoToolInvokeFn invoke, PantoToolDestroyFn destroy);
PANTO_EXPORT PantoStatus panto_agent_register_tool_source(PantoAgent *agent, PantoSlice name, const PantoToolDecl *decls, size_t len, void *ctx, PantoToolSourceInvokeBatchFn invoke_batch, PantoToolDestroyFn destroy);
PANTO_EXPORT PantoResultParts panto_result_parts_text(const char *text);
PANTO_EXPORT void panto_result_parts_destroy(PantoResultParts parts);
#ifdef __cplusplus
}
#endif
#endif