import type { Session, ToolCall } from '../../types/api.js';
import * as modelContext from '../model-context.js';
import { PathScopeError } from '../path_guard.js';
import { TOOLS_BY_NAME } from '../tools.js';
import { maybeFlagForCompaction } from './payload.js';
import { insertParts, partsFromAssistantMessage, partsFromToolMessage } from './parts.js';
import type {
  InferenceContext,
  StreamResult,
  TurnArgs,
} from './turn.js';
// v1.12.4: ESM value-import cycle. executeToolPhase recurses into
// runAssistantTurn which lives in inference.ts. The cycle is safe because
// the reference is read at call time (inside an async function body), not
// at module top-level. Node + tsc resolve this cleanly.
import { runAssistantTurn } from './turn.js';

async function executeToolCall(
  projectRoot: string,
  toolCall: ToolCall
): Promise<{ output: unknown; truncated: boolean; error?: string }> {
  const tool = TOOLS_BY_NAME[toolCall.name];
  if (!tool) {
    return { output: null, truncated: false, error: `unknown tool: ${toolCall.name}` };
  }
  const parsed = tool.inputSchema.safeParse(toolCall.args);
  if (!parsed.success) {
    // v1.12 Track B.2: enrich the zod-reject path so the model sees a
    // one-line, tool-named hint ("tool 'search_symbols' rejected — query:
    // Required") instead of a JSON blob of flatten output. Higher recovery
    // rate on the next turn; doom-loop guard still bounds infinite retries.
    // The cast is because tool.inputSchema is ZodType<unknown>, so zod can't
    // statically narrow flatten()'s fieldErrors key set — but the runtime
    // shape is the standard { formErrors: string[]; fieldErrors: Record<...> }.
    const flatten = parsed.error.flatten() as {
      formErrors: string[];
      fieldErrors: Record<string, string[] | undefined>;
    };
    const fieldErrors = Object.entries(flatten.fieldErrors)
      .map(([field, errs]) => `${field}: ${errs?.[0] ?? 'invalid'}`)
      .join('; ');
    const formError = flatten.formErrors[0];
    const hint = fieldErrors || formError || 'unknown validation error';
    return {
      output: null,
      truncated: false,
      error: `tool '${toolCall.name}' rejected — ${hint}`,
    };
  }
  try {
    const output = await tool.execute(parsed.data, projectRoot);
    const truncated =
      typeof output === 'object' && output !== null && 'truncated' in output
        ? Boolean((output as { truncated: unknown }).truncated)
        : false;
    return { output, truncated };
  } catch (err) {
    if (err instanceof PathScopeError) {
      return { output: null, truncated: false, error: err.message };
    }
    return {
      output: null,
      truncated: false,
      error: err instanceof Error ? err.message : String(err),
    };
  }
}

export async function executeToolPhase(
  ctx: InferenceContext,
  args: TurnArgs,
  result: StreamResult,
  startedAt: string | null,
  session: Session,
  projectRoot: string
): Promise<void> {
  const { sessionId, chatId, assistantMessageId, toolsUsed, signal } = args;
  const { content, toolCalls, promptTokens, completionTokens } = result;

  // v1.11.3: ctx_max comes from llama-swap /upstream/<model>/props, not the
  // streaming completion (which doesn't emit n_ctx). getModelContext caches
  // the positive lookup for the process lifetime, so this is a single Map
  // hit after the first invocation per model.
  const mctx = await modelContext.getModelContext(session.model);
  const nCtx = mctx?.n_ctx ?? null;

  const [updated] = await ctx.sql<
    { tokens_used: number | null; ctx_used: number | null; ctx_max: number | null; finished_at: string | null }[]
  >`
    UPDATE messages
    SET content = ${content},
        status = 'complete',
        tool_calls = ${ctx.sql.json(toolCalls as never)},
        tokens_used = ${completionTokens},
        ctx_used = ${promptTokens},
        ctx_max = ${nCtx},
        finished_at = clock_timestamp()
    WHERE id = ${assistantMessageId}
    RETURNING tokens_used, ctx_used, ctx_max, finished_at
  `;
  // v1.13.0: dual-write to message_parts. v1.13.1-B made parts authoritative
  // for reads via the messages_with_parts view; the JSON column write above
  // remains for v1.13.1 fallback compatibility (dropped in v1.13.2).
  // v1.13.1-C: include result.reasoning so models with separate reasoning
  // channels (qwen3.6) get a kind='reasoning' part at sequence 0.
  // TODO(v1.13.1): wrap the UPDATE above and this insertParts in a single
  // sql.begin before flipping read authority to message_parts. Without the
  // transaction, a crash between the two leaves an orphan message that
  // becomes invisible in the parts-authoritative read path.
  await insertParts(
    ctx.sql,
    partsFromAssistantMessage({
      content,
      tool_calls: toolCalls,
      reasoning: result.reasoning,
    }).map((p) => ({
      ...p,
      message_id: assistantMessageId,
    })),
  );
  // v1.11: flag for compaction if this turn pushed us over the usable budget.
  // We never compact mid-loop (the recursive runAssistantTurn keeps tools
  // flowing); the flag fires on the NEXT turn's pre-fetch hook above.
  await maybeFlagForCompaction(ctx, chatId, updated);
  const [toolSessRow] = await ctx.sql<{ project_id: string; name: string; updated_at: string }[]>`
    UPDATE sessions SET updated_at = clock_timestamp()
    WHERE id = ${sessionId}
    RETURNING project_id, name, updated_at
  `;
  ctx.publishUser({ type: 'session_updated', session_id: sessionId, project_id: toolSessRow!.project_id, name: toolSessRow!.name, updated_at: toolSessRow!.updated_at });
  for (const tc of toolCalls) {
    ctx.publish(sessionId, {
      type: 'tool_call',
      message_id: assistantMessageId,
      chat_id: chatId,
      tool_call: tc,
    });
  }
  ctx.publish(sessionId, {
    type: 'message_complete',
    message_id: assistantMessageId,
    chat_id: chatId,
    tokens_used: updated?.tokens_used ?? null,
    ctx_used: updated?.ctx_used ?? null,
    ctx_max: updated?.ctx_max ?? null,
    started_at: startedAt,
    finished_at: updated?.finished_at ?? null,
    model: session.model,
  });

  // Batch 9.7: ask_user_input pauses the loop. The tool row is still inserted
  // (the answer endpoint needs a target row to UPDATE), but tool_results is
  // pre-stamped with output=null as a "pending" sentinel and no tool_result
  // frame goes out — the card renders from the tool_call frame alone. Mixed
  // batches still execute the other tools normally.
  ctx.publishUser({ type: 'chat_status', chat_id: chatId, status: 'tool_running', at: new Date().toISOString() });
  let pausingForUserInput = false;
  await Promise.all(
    toolCalls.map(async (tc) => {
      const [toolRow] = await ctx.sql<{ id: string }[]>`
        INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
        VALUES (${sessionId}, ${chatId}, 'tool', '', 'complete', clock_timestamp())
        RETURNING id
      `;
      const toolMessageId = toolRow!.id;
      if (tc.name === 'ask_user_input') {
        pausingForUserInput = true;
        const sentinel = { tool_call_id: tc.id, output: null, truncated: false };
        await ctx.sql`
          UPDATE messages
          SET tool_results = ${ctx.sql.json(sentinel as never)}
          WHERE id = ${toolMessageId}
        `;
        // v1.13.0: mirror the pending sentinel into message_parts. The
        // answer-endpoint UPDATE later (messages.ts:576) will delete and
        // re-insert this part when the user submits their answer.
        // TODO(v1.13.1): wrap the INSERT + UPDATE + insertParts triple in
        // a per-iteration sql.begin before flipping read authority.
        await insertParts(
          ctx.sql,
          partsFromToolMessage({ tool_results: sentinel }).map((p) => ({
            ...p,
            message_id: toolMessageId,
          })),
        );
        return;
      }
      const tres = await executeToolCall(projectRoot, tc);
      const stored = {
        tool_call_id: tc.id,
        output: tres.output,
        truncated: tres.truncated,
        ...(tres.error ? { error: tres.error } : {}),
      };
      await ctx.sql`
        UPDATE messages
        SET tool_results = ${ctx.sql.json(stored as never)}
        WHERE id = ${toolMessageId}
      `;
      // v1.13.0: dual-write the tool_result part.
      // TODO(v1.13.1): wrap the INSERT + UPDATE + insertParts triple in a
      // per-iteration sql.begin before flipping read authority.
      await insertParts(
        ctx.sql,
        partsFromToolMessage({ tool_results: stored }).map((p) => ({
          ...p,
          message_id: toolMessageId,
        })),
      );
      ctx.publish(sessionId, {
        type: 'tool_result',
        tool_message_id: toolMessageId,
        chat_id: chatId,
        tool_call_id: tc.id,
        output: tres.output,
        truncated: tres.truncated,
        ...(tres.error ? { error: tres.error } : {}),
      });
    })
  );

  if (pausingForUserInput) {
    ctx.publishUser({
      type: 'chat_status',
      chat_id: chatId,
      status: 'waiting_for_input',
      at: new Date().toISOString(),
    });
    ctx.log.info(
      { sessionId, chatId, assistantMessageId },
      'inference paused awaiting user input',
    );
    return;
  }

  const [nextAssistant] = await ctx.sql<{ id: string }[]>`
    INSERT INTO messages (session_id, chat_id, role, content, status, created_at)
    VALUES (${sessionId}, ${chatId}, 'assistant', '', 'streaming', clock_timestamp())
    RETURNING id
  `;
  await runAssistantTurn(ctx, {
    sessionId,
    chatId,
    assistantMessageId: nextAssistant!.id,
    // v1.8.2: charge this turn's actual tool invocations against the budget.
    // One assistant message can emit multiple tool_calls, so we add the run
    // count, not 1. The next turn's budget check sees the cumulative total.
    toolsUsed: toolsUsed + result.toolCalls.length,
    // v1.11.6: append the just-executed tool calls to the per-turn history
    // so the next runAssistantTurn's doom-loop check can see them. We don't
    // cap the array length here — per-turn budgets keep it bounded
    // (typically <30 entries), and slicing happens inside detectDoomLoop.
    recentToolCalls: [...args.recentToolCalls, ...result.toolCalls],
    signal,
  });
}