/**
 * POST /api/chat
 *
 * Streaming chat endpoint. Accepts a thread_id + user message,
 * loads history, calls Gemini 3.1 Pro, runs the tool loop,
 * persists messages, and streams SSE back to the client.
 *
 * SSE event shapes:
 *   data: {"type":"text","text":"..."}
 *   data: {"type":"tool_start","name":"...","args":{}}
 *   data: {"type":"tool_result","name":"...","result":"..."}
 *   data: {"type":"done"}
 *   data: {"type":"error","error":"..."}
 */
import { NextResponse } from 'next/server';
import { authSession } from '@/lib/auth/session-server';
import { query } from '@/lib/db-postgres';
import { callGeminiChat, streamGeminiChat } from '@/lib/ai/gemini-chat';
import { VIBN_TOOL_DEFINITIONS, executeMcpTool } from '@/lib/ai/vibn-tools';
import type { ChatMessage, ToolCall } from '@/lib/ai/gemini-chat';

// Bumped from 6 to 12 because Path B chains (devcontainer.ensure →
// fs.read → fs.edit → kill → start → curl → logs) routinely fire 7-10
// tool calls in one user turn. When the cap IS hit, we still emit a
// narrative summary instead of leaving the user staring at a tool tray
// (see the no-tools follow-up call below).
const MAX_TOOL_ROUNDS = 18;

let chatTablesReady = false;
async function ensureChatTables() {
  if (chatTablesReady) return;
  await query(`
    CREATE TABLE IF NOT EXISTS fs_chat_threads (
      id         TEXT PRIMARY KEY DEFAULT gen_random_uuid()::text,
      user_id    TEXT NOT NULL,
      workspace  TEXT NOT NULL DEFAULT '',
      data       JSONB NOT NULL DEFAULT '{}',
      created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
      updated_at TIMESTAMPTZ NOT NULL DEFAULT now()
    );
    CREATE INDEX IF NOT EXISTS fs_chat_threads_user_ws_idx
      ON fs_chat_threads (user_id, workspace, updated_at DESC);

    CREATE TABLE IF NOT EXISTS fs_chat_messages (
      id         BIGSERIAL PRIMARY KEY,
      thread_id  TEXT NOT NULL REFERENCES fs_chat_threads(id) ON DELETE CASCADE,
      user_id    TEXT NOT NULL,
      data       JSONB NOT NULL DEFAULT '{}',
      created_at TIMESTAMPTZ NOT NULL DEFAULT now()
    );
    CREATE INDEX IF NOT EXISTS fs_chat_messages_thread_idx
      ON fs_chat_messages (thread_id, created_at ASC);
  `, []);
  chatTablesReady = true;
}

function buildSystemPrompt(projects: any[], workspace: string): string {
  const projectsText = projects.length
    ? projects
        .map(
          (p: any) =>
            `- "${p.productName || p.name}" (id: ${p.id}, status: ${p.status || 'defining'})${p.productVision ? ': ' + p.productVision.slice(0, 120) : ''}`,
        )
        .join('\n')
    : '(no projects yet)';

  return `You are Vibn AI, an expert product and infrastructure assistant embedded in the Vibn platform.
You are talking to the owner of the "${workspace}" workspace.

## How Vibn is structured
- **Workspace** ("${workspace}") — the tenant boundary. One per user. Owns the Gitea org and a fleet of Coolify projects. You can ONLY see and touch resources in this workspace.
- **Project** — an initiative the user is building (e.g. "Twenty CRM", "My Blog"). Each project has its OWN isolated Coolify project, so all its apps + databases + services are grouped together. A project has two facets that are part of ONE thing — never describe them as separate:
  - Planning side: name, vision/objectives, requirements (from \`projects_get\`)
  - Live side: deployed apps + services (from \`projects_get → possibleDeployments[]\` and \`apps_list { projectId }\`)

## How to answer questions
- "What is project X?" → \`projects_get { id }\`. The result includes both planning details and the linked deployments.
- "What's running / what has a domain?" → \`apps_list\` (no args) for everything in the workspace, or \`apps_list { projectId }\` for one project.
- "Show me logs / containers / env" → resolve the app uuid first via \`apps_list\`, then call \`apps_logs\` / \`apps_containers_list\` / \`apps_envs_list\`.
- "Find an open source X" → \`github_search\` (always include \`license:mit\` unless the user says otherwise), then \`github_file\` to read READMEs / docker-compose.yml / design system entry points before recommending.
- "What's our docs say about Y?" → \`http_fetch\` against the relevant URL.

## How to deploy

**Third-party app (Twenty CRM, n8n, Ghost, Supabase, Pocketbase, etc.)**
1. \`apps_templates_search { query }\` — find the official one-click template.
2. \`apps_create { projectId, name, template, domain }\` — deploy from template into the right project's Coolify namespace.
3. Watch \`apps_get { uuid }\` for status; surface the live URL once \`fqdn\` is set.

**Custom Docker image**
1. \`apps_create { projectId, name, dockerImage, domain, envsJson }\`.
2. \`apps_deploy { uuid }\` if it doesn't auto-deploy.

**Database**
1. \`databases_create { projectId, name, type }\` (type: postgres, mysql, redis, mongodb, mariadb, dragonfly, clickhouse, keydb).
2. \`databases_get { uuid }\` returns the internal connection URL — inject it into the app via \`apps_envs_set\`.

**Domain**
1. \`domains_search { query }\` to check availability + price.
2. \`domains_register { domain }\` to buy it (uses workspace billing).
3. \`apps_domains_set { uuid, domains }\` to attach. DNS + Traefik are wired automatically.

## Writing code (PREFERRED: dev container, shell-first)

Each Vibn project has a persistent **dev container** (\`vibn-dev\`) running on Coolify. You write code by \`shell_exec\`-ing inside it and editing files with \`fs_*\` tools. This is dramatically faster than committing to Gitea and waiting for redeploys (sub-second feedback vs ~5 min).

**Always start a coding session with**:
1. \`devcontainer_ensure { projectId }\` — idempotent. First call ~10s (provisions a Coolify service); subsequent calls return immediately.

**Then iterate with**:
- \`shell_exec { projectId, command }\` — run anything: \`ls\`, \`npm install\`, \`npm test\`, \`mise install\` (installs Node/Python/Go/Rust on first use), \`npx create-next-app .\`, \`git status\`. Cwd defaults to \`/workspace\`.
- \`fs_read { projectId, path }\` — inspect a file.
- \`fs_write { projectId, path, content }\` — create or overwrite a file.
- \`fs_edit { projectId, path, oldString, newString }\` — surgical search/replace. Include 2-3 lines of surrounding context in \`oldString\` so the match is unique. Fails fast if missing or non-unique.
- \`fs_glob\` / \`fs_grep\` — find files by pattern, search code by regex (ripgrep, respects .gitignore).
- \`fs_list\`, \`fs_delete\` — directory listing, delete.

**Dev servers (preview URLs)**:
- \`dev_server_start { projectId, command, port }\` — \`port\` MUST be in the range **3000-3009** (only 10 ports per project have pre-allocated Traefik routers). Pick 3000 for the primary app; use 3001-3009 only when the user is running multiple servers concurrently (e.g. frontend + API). The returned \`previewUrl\` is the public URL once DNS is wired.
- \`dev_server_stop { projectId, id }\`, \`dev_server_list { projectId }\`, \`dev_server_logs { projectId, id }\`.
- If \`dev_server_start\` returns \`code: PORT_BUSY\` → either stop the existing server first or pick another port in 3000-3009. Don't blindly retry the same port.

**Framework-specific HMR setup** (so hot reload works through the preview URL once DNS is live — apply when scaffolding):
- **Vite**: \`server.host: '0.0.0.0'\`, \`server.hmr.clientPort: 443\`, \`server.hmr.protocol: 'wss'\`. Vite's default localhost binding will appear to work but break HMR through Traefik.
- **Next dev**: \`next dev -p 3000 -H 0.0.0.0\`. Next handles WSS HMR automatically through proxies.
- **Express / plain Node**: bind \`0.0.0.0\` (we set \`HOST=0.0.0.0\` env automatically, but verify the framework respects it).

**End-to-end recipe for "build me X"**:
1. \`devcontainer_ensure { projectId }\`.
2. \`shell_exec { projectId, command: 'npx create-next-app@latest . --yes' }\` (or whichever scaffold fits — search GitHub first if the user wants an OSS starting point).
3. \`shell_exec\` to run \`npm install\`, then iterate with \`fs_edit\` / \`fs_write\` to customize.
4. \`shell_exec { command: 'npm run dev -- --port 3000' }\` to verify locally (preview URLs land in week 2).
5. When the user says "ship it" — for now, \`shell_exec\` a \`git add . && git commit -m "..." && git push\` to push to the Gitea repo, then \`apps_create\` to wire up the production deployment. (A dedicated \`ship\` tool lands soon.)

**Rules**:
- Stay under \`/workspace\`. The fs_* tools enforce this; for system paths use \`shell_exec\` deliberately.
- The container has no route to internal Vibn services (vibn-postgres, etc.) by design.
- If \`shell_exec\` returns non-zero, READ THE STDERR before re-running; don't loop blindly.

## Gitea repo orchestration (one-time setup)
For creating new repos, branching, and listing what already exists:
- \`gitea_repos_list\`, \`gitea_repo_get\`, \`gitea_repo_create\`.
- \`gitea_branches_list\`, \`gitea_branch_create\`.

For all file editing inside an existing repo, ALWAYS use \`fs_*\` against the dev container. The \`ship\` tool will then push your changes to Gitea in one commit.

## Troubleshooting
- Deploy stuck or "exited (1)" → \`apps_logs { uuid }\` and \`apps_containers_list { uuid }\`. Common causes: missing env var, wrong port, image pull failure.
- 502 / "no available server" → app probably has no public domain yet. Check \`apps_get\`; if \`fqdn\` is empty, attach a domain.
- "tenant" / "does not belong to" errors → the uuid you passed isn't in this workspace. Re-list with \`apps_list\` to grab a valid one.
- Compose stack acting weird → \`apps_repair { uuid }\` to re-apply post-deploy fixes (Traefik labels, port forwarding).
- Need to nuke and re-deploy → \`apps_delete { uuid, confirm }\` (confirm must equal the app's exact name; fetch via \`apps_get\` first), then re-create.

## Hard rules
- ALWAYS pass \`projectId\` to \`apps_create\` and \`databases_create\`. If the user didn't say which project, ask once, then proceed.
- ALWAYS call \`apps_templates_search\` BEFORE \`apps_create\` when the user names a known third-party app — don't hand-roll a Docker image when a maintained template exists.
- Destructive ops (\`*_delete\`, \`*_volumes_wipe\`) require \`confirm\` equal to the resource's exact name. Always fetch the name first with a \`*_get\` call.
- Long-running ops (deploys, DNS provisioning, db provisioning) take 1–5 min. Tell the user up front so they don't think you're stuck.
- Be concise and action-oriented. If the user says "deploy X", do it — don't write a tutorial.
- After every tool call, summarize the result in 1–2 sentences. Don't dump raw JSON unless asked.
- Format app names, URLs, env keys, UUIDs, and file paths in backticks.
- If a tool errors and you don't understand why, say so honestly and suggest the next diagnostic call.

## Current workspace projects
${projectsText}

Today's date: ${new Date().toLocaleDateString('en-US', { weekday: 'long', year: 'numeric', month: 'long', day: 'numeric' })}.`;
}

export async function POST(request: Request) {
  await ensureChatTables();

  const session = await authSession();
  if (!session?.user?.email) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
  }

  let body: { thread_id: string; message: string; workspace: string; mcp_token?: string };
  try {
    body = await request.json();
  } catch {
    return NextResponse.json({ error: 'Invalid JSON' }, { status: 400 });
  }

  const { thread_id, message, workspace, mcp_token } = body;
  if (!thread_id || !message?.trim()) {
    return NextResponse.json({ error: 'thread_id and message are required' }, { status: 400 });
  }

  const email = session.user.email;

  // Verify thread belongs to user
  const threads = await query<any>(
    `SELECT id FROM fs_chat_threads WHERE id = $1 AND user_id = $2`,
    [thread_id, email],
  );
  if (!threads.length) {
    return NextResponse.json({ error: 'Thread not found' }, { status: 404 });
  }

  // Load message history (last 40 messages)
  const rows = await query<any>(
    `SELECT data FROM fs_chat_messages WHERE thread_id = $1 ORDER BY created_at DESC LIMIT 40`,
    [thread_id],
  );
  const history: ChatMessage[] = rows.reverse().map((r: any) => r.data);

  // Add user message
  const userMsg: ChatMessage = { role: 'user', content: message.trim() };
  history.push(userMsg);
  await query(
    `INSERT INTO fs_chat_messages (thread_id, user_id, data) VALUES ($1, $2, $3)`,
    [thread_id, email, JSON.stringify(userMsg)],
  );

  // Update thread updatedAt
  await query(
    `UPDATE fs_chat_threads SET updated_at = NOW(), data = data || $2 WHERE id = $1`,
    [thread_id, JSON.stringify({ updatedAt: new Date().toISOString() })],
  );

  // Load projects for system prompt context
  const projectRows = await query<any>(
    `SELECT p.data FROM fs_projects p
     JOIN fs_users u ON u.id = p.user_id
     WHERE u.data->>'email' = $1
     ORDER BY (p.data->>'updatedAt') DESC NULLS LAST LIMIT 20`,
    [email],
  );
  const projects = projectRows.map((r: any) => r.data);
  const systemPrompt = buildSystemPrompt(projects, workspace);

  // Base URL for internal MCP calls
  const host = request.headers.get('host') || 'vibnai.com';
  const proto = host.startsWith('localhost') ? 'http' : 'https';
  const baseUrl = `${proto}://${host}`;

  // Honor client-side abort (Stop button). When the user clicks Stop
  // the browser's AbortController fires `request.signal.aborted` and
  // the fetch stream is closed; we use it as a polite checkpoint
  // between rounds and tool calls so we (a) don't keep paying Gemini
  // for tokens the user no longer wants and (b) persist whatever the
  // assistant produced before the cancel.
  const clientSignal = request.signal;

  // Stream response
  const encoder = new TextEncoder();
  const stream = new ReadableStream({
    async start(controller) {
      let streamClosed = false;
      function emit(chunk: object) {
        if (streamClosed) return;
        try {
          controller.enqueue(encoder.encode(`data: ${JSON.stringify(chunk)}\n\n`));
        } catch {
          // controller may have been closed by the abort handler
          streamClosed = true;
        }
      }
      function safeClose() {
        if (streamClosed) return;
        streamClosed = true;
        try {
          controller.close();
        } catch {}
      }

      let messages = [...history];
      let round = 0;
      let assistantText = '';
      const assistantToolCalls: ToolCall[] = [];
      let aborted = clientSignal.aborted;
      const onAbort = () => {
        aborted = true;
      };
      clientSignal.addEventListener('abort', onAbort);

      try {
        // Tool-calling loop: use non-streaming so thought_signature is
        // always present in the complete response (required by thinking models).
        while (round < MAX_TOOL_ROUNDS) {
          if (aborted) break;
          round++;

          const toolDefs = mcp_token ? VIBN_TOOL_DEFINITIONS : [];
          const resp = await callGeminiChat({ systemPrompt, messages, tools: toolDefs, temperature: 0.7 });

          if (resp.error) {
            emit({ type: 'error', error: resp.error });
            controller.close();
            return;
          }

          // Stream text to client
          if (resp.text) {
            assistantText += resp.text;
            emit({ type: 'text', text: resp.text });
          }

          // Announce tool calls
          for (const tc of resp.toolCalls) {
            assistantToolCalls.push(tc);
            emit({ type: 'tool_start', name: tc.name, args: tc.args });
          }

          // Save assistant turn
          messages.push({
            role: 'assistant',
            content: resp.text,
            toolCalls: resp.toolCalls.length ? resp.toolCalls : undefined,
          });

          if (!resp.toolCalls.length) break;
          if (aborted) break;

          // Execute tool calls and add results
          for (const tc of resp.toolCalls) {
            if (aborted) break;
            const result = mcp_token
              ? await executeMcpTool(tc.name, tc.args, mcp_token, baseUrl)
              : JSON.stringify({ error: 'No MCP token — read-only mode.' });

            emit({ type: 'tool_result', name: tc.name, result: result.slice(0, 500) });

            messages.push({
              role: 'tool',
              content: result,
              toolCallId: tc.id,
              toolName: tc.name,
              thoughtSignature: tc.thoughtSignature,
            });
          }
        }

        // If the user clicked Stop, surface the cancel marker so the
        // client renders "(stopped by user)" inline with the partial
        // assistant message, then skip the round-cap recovery summary
        // (we shouldn't pay Gemini for a turn the user just canceled).
        if (aborted) {
          const stopMarker = assistantText
            ? '\n\n_(stopped by user)_'
            : '_(stopped by user before any response)_';
          assistantText += stopMarker;
          emit({ type: 'text', text: stopMarker });
          emit({ type: 'aborted' });
        }

        // If the loop exited because we hit MAX_TOOL_ROUNDS while the
        // model still wanted to call tools, the user has only seen a
        // tray of ✓ icons with no narrative. Force one final no-tools
        // call so we always end on a human-readable summary.
        const lastTurnHadTools =
          messages.length > 0 &&
          messages[messages.length - 1].role === 'tool';
        if (!aborted && round >= MAX_TOOL_ROUNDS && lastTurnHadTools) {
          try {
            const summary = await callGeminiChat({
              systemPrompt:
                systemPrompt +
                '\n\nYou have just executed a chain of tool calls. Summarize the result for the user in 1-3 sentences. Do NOT call any more tools.',
              messages,
              tools: [],
              temperature: 0.3,
            });
            if (summary.text) {
              assistantText += summary.text;
              emit({ type: 'text', text: summary.text });
            }
          } catch {
            // Don't let a failed summary kill the stream.
          }
        }

        // Persist final assistant message
        const finalMsg: ChatMessage = {
          role: 'assistant',
          content: assistantText,
          toolCalls: assistantToolCalls.length ? assistantToolCalls : undefined,
        };
        await query(
          `INSERT INTO fs_chat_messages (thread_id, user_id, data) VALUES ($1, $2, $3)`,
          [thread_id, email, JSON.stringify(finalMsg)],
        );

        emit({ type: 'done' });
        safeClose();
      } catch (e) {
        // AbortError is the expected shape when the client cancels
        // mid-Gemini-call — don't surface it as a real error.
        const isAbort =
          aborted ||
          (e instanceof Error && (e.name === 'AbortError' || /aborted/i.test(e.message)));
        if (!isAbort) {
          emit({ type: 'error', error: e instanceof Error ? e.message : String(e) });
        } else {
          emit({ type: 'aborted' });
        }
        safeClose();
      } finally {
        clientSignal.removeEventListener('abort', onAbort);
      }
    },
    cancel() {
      // Browser disconnected (tab closed, navigated away). Nothing to
      // do — the abort handler above already flipped the flag and the
      // loop will bail at the next checkpoint.
    },
  });

  return new Response(stream, {
    headers: {
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      Connection: 'keep-alive',
    },
  });
}