import http from "node:http";
import { randomUUID } from "node:crypto";
import type { BridgeInboundRequest } from "../core/types/model.js";
import {
  buildSessionKey,
  extractLatestUserMessage,
  extractRequestContext,
  resolveDispatchPrompt,
} from "./input-filter.js";
import { buildBootstrap } from "./bootstrap.js";
import { dispatchToClaude } from "../core/claude/sdk-adapter.js";
import { dispatchToGemini } from "../core/gemini/sdk-adapter.js";
import { getGlobalPluginRegistry } from "openclaw/plugin-sdk/plugin-runtime";
import {
  getSession,
  putSession,
  markOrphaned,
  removeSession,
} from "../core/contractor/session-map-store.js";

export type BridgeServerConfig = {
  port: number;
  apiKey: string;
  permissionMode: string;
  /** Fallback: resolve workspace from agent id if not parseable from system prompt */
  resolveAgent?: (
    agentId: string,
    sessionKey: string,
  ) => { workspace: string } | null;
  logger: { info: (msg: string) => void; warn: (msg: string) => void };
};

function sendJson(res: http.ServerResponse, status: number, body: unknown): void {
  const json = JSON.stringify(body);
  res.writeHead(status, {
    "Content-Type": "application/json; charset=utf-8",
    "Content-Length": Buffer.byteLength(json),
  });
  res.end(json);
}

/** Write a single SSE data line. */
function sseWrite(res: http.ServerResponse, data: string): void {
  res.write(`data: ${data}\n\n`);
}

/** Build an OpenAI streaming chunk for a text delta. */
function buildChunk(id: string, text: string): string {
  return JSON.stringify({
    id,
    object: "chat.completion.chunk",
    created: Math.floor(Date.now() / 1000),
    model: "contractor-claude-bridge",
    choices: [{ index: 0, delta: { content: text }, finish_reason: null }],
  });
}

/** Build the final stop chunk. */
function buildStopChunk(id: string): string {
  return JSON.stringify({
    id,
    object: "chat.completion.chunk",
    created: Math.floor(Date.now() / 1000),
    model: "contractor-claude-bridge",
    choices: [{ index: 0, delta: {}, finish_reason: "stop" }],
  });
}

function parseBodyRaw(req: http.IncomingMessage): Promise<unknown> {
  return new Promise((resolve, reject) => {
    let body = "";
    req.on("data", (chunk: Buffer) => {
      body += chunk.toString("utf8");
      if (body.length > 4_000_000) req.destroy(new Error("body too large"));
    });
    req.on("end", () => {
      try {
        resolve(JSON.parse(body));
      } catch (e) {
        reject(e);
      }
    });
    req.on("error", reject);
  });
}

function parseBody(req: http.IncomingMessage): Promise<BridgeInboundRequest> {
  return parseBodyRaw(req) as Promise<BridgeInboundRequest>;
}

/**
 * Per-sessionKey FIFO queue: same-session turns serialize so a user firing
 * multiple Discord messages back-to-back gets them processed in order rather
 * than spawning concurrent claude subprocesses. Cross-session requests bypass
 * each other's chains and run in parallel.
 *
 * The chain is `prev.then(() => mySlot)` per request — `mySlot` is released
 * in the request's finally block, so the next request waits until our work
 * completes (success or failure) before starting.
 */
const queueBySession = new Map<string, Promise<void>>();

/**
 * SSE keepalive cadence. Bridge writes `: keepalive\n\n` (an SSE comment
 * frame, no-op for the OpenAI stream parser) on this interval while a turn
 * is in flight or queued. This keeps OpenClaw's LLM idle watchdog (default
 * 120s of stream silence → attempt failure → retry) from firing when the
 * underlying claude subprocess is in a long quiet tool-call phase or while
 * we're waiting our turn in the per-session queue.
 */
const HEARTBEAT_MS = 30_000;

const _G = globalThis as Record<string, unknown>;

export function createBridgeServer(config: BridgeServerConfig): http.Server {
  const { port, apiKey, permissionMode, resolveAgent, logger } = config;

  async function handleChatCompletions(
    req: http.IncomingMessage,
    res: http.ServerResponse,
  ): Promise<void> {
    let body: BridgeInboundRequest;
    try {
      body = await parseBody(req);
    } catch {
      sendJson(res, 400, { error: "invalid_json" });
      return;
    }

    // Extract agent ID, workspace, chat id, and bare-reset signal from the
    // request. OpenClaw does NOT send agent/session info as HTTP headers — it
    // lives in the system prompt's Runtime line and the user envelope's
    // "Conversation info" untrusted-metadata block.
    const {
      agentId: parsedAgentId,
      workspace: parsedWorkspace,
      skillsBlock,
      workspaceContextFiles,
      chatId,
      bareSessionReset,
    } = extractRequestContext(body);
    const latestMessage = extractLatestUserMessage(body);

    // Pick the prompt to forward to the CLI. For bare /new turns OpenClaw
    // submits an empty user message — we synthesize a stub prompt instead so
    // the CLI has something to respond to.
    const dispatchPrompt = resolveDispatchPrompt(latestMessage, { bareSessionReset });

    if (!dispatchPrompt) {
      sendJson(res, 400, { error: "no user message found" });
      return;
    }

    // Scope the CLI session by (agentId, chat_id) so different Discord
    // channels / DMs / etc. for the same agent don't pile into one Claude
    // session and bleed context across surfaces. Falls back to agentId-only
    // when chat_id can't be parsed (local TUI, etc.).
    const agentId = parsedAgentId;
    const sessionKey = buildSessionKey(agentId, chatId);

    logger.info(
      `[contractor-bridge] turn agentId=${agentId} sessionKey=${sessionKey} workspace=${parsedWorkspace} bareReset=${bareSessionReset} msg=${dispatchPrompt.substring(0, 80)}`,
    );

    // Resolve workspace: prefer what we parsed from the system prompt (most accurate);
    // fall back to openclaw.json lookup for validation.
    let workspace = parsedWorkspace;
    if (!workspace && agentId) {
      const agentMeta = resolveAgent?.(agentId, sessionKey);
      if (agentMeta) workspace = agentMeta.workspace;
    }
    if (!workspace) {
      logger.warn(`[contractor-bridge] could not resolve workspace agentId=${agentId}`);
      workspace = "/tmp";
    }

    // Detect backend from body.model: "contractor-gemini-bridge" → Gemini, else → Claude
    const isGemini = typeof body.model === "string" && body.model.includes("gemini");

    // ── Abort propagation ────────────────────────────────────────────────────
    // OpenClaw's LLM client cancels in-flight HTTP requests via AbortSignal
    // when an attempt fails or the user cancels. On the wire this manifests
    // as the client closing the socket, surfaced here as `req.on('close')`.
    // We mirror that signal into our own AbortController and propagate it
    // down to the dispatchTo{Claude,Gemini} adapter, which kills the
    // subprocess. Without this, OpenClaw silently drops the response while
    // the subprocess keeps running, and a retry spawns another subprocess
    // alongside the orphan — the root cause of the duplicate-Discord-message
    // bug we hit in May 2026.
    const abortController = new AbortController();
    let clientDisconnected = false;
    const onClose = (): void => {
      if (clientDisconnected) return;
      clientDisconnected = true;
      logger.info(
        `[contractor-bridge] client disconnected sessionKey=${sessionKey} — aborting in-flight work`,
      );
      abortController.abort();
    };
    req.on("close", onClose);

    // Start SSE response immediately so OpenClaw sees the response status
    // quickly. We may still spend time waiting in the per-session queue
    // before any real chunk goes out — heartbeat (below) keeps that quiet
    // window from tripping the upstream idle watchdog.
    res.writeHead(200, {
      "Content-Type": "text/event-stream",
      "Cache-Control": "no-cache",
      "Connection": "keep-alive",
      "Transfer-Encoding": "chunked",
    });

    // ── SSE heartbeat ────────────────────────────────────────────────────────
    // OpenClaw's idle timeout fires after 120s of total stream silence with
    // no model progress (`LLM idle timeout (120s): no response from model`).
    // claude -p can easily produce 120s+ of zero assistant-text output during
    // long Bash / file / MCP tool sequences, since this bridge only forwards
    // assistant text deltas as SSE chunks (tool_use blocks are not surfaced).
    // A periodic SSE comment frame counts as bytes on the wire and resets
    // the upstream idle timer, while being a no-op for the OpenAI stream
    // parser.
    const heartbeat = setInterval(() => {
      if (clientDisconnected || res.writableEnded) return;
      try {
        res.write(": keepalive\n\n");
      } catch {
        /* socket dead, ignore */
      }
    }, HEARTBEAT_MS);
    heartbeat.unref?.();

    // ── Per-sessionKey FIFO queue ────────────────────────────────────────────
    // Same-sessionKey turns serialize: if a user fires multiple Discord
    // messages quickly, we process them in order rather than starting
    // concurrent claude subprocesses (which would corrupt the shared session
    // file and produce overlapping replies). Cross-sessionKey requests run
    // in parallel — they live on independent chains.
    let releaseSlot: () => void = () => {};
    const mySlot = new Promise<void>((r) => {
      releaseSlot = r;
    });
    const prev = sessionKey
      ? queueBySession.get(sessionKey) ?? Promise.resolve()
      : Promise.resolve();
    // `myChainTail` advances only after `releaseSlot()` (called in our
    // finally block). Tolerate prev rejecting so a crashed earlier turn
    // doesn't poison the chain forever.
    const myChainTail = prev.then(() => mySlot, () => mySlot);
    if (sessionKey) queueBySession.set(sessionKey, myChainTail);

    const completionId = `chatcmpl-bridge-${randomUUID().slice(0, 8)}`;
    let newSessionId = "";
    let hasError = false;
    let resultErrorReason: string | null = null;
    let existingEntry: ReturnType<typeof getSession> = null;

    try {
      // Block until the previous turn on this sessionKey finishes.
      // Cross-session requests skip this wait (their `prev` is a fresh
      // Promise.resolve()).
      await prev.catch(() => {});

      // While queued, OpenClaw may have given up on this request (attempt
      // timeout, user cancel, etc.) and closed the socket. If so, exit
      // cleanly without dispatching — the client wouldn't see the output
      // anyway.
      if (clientDisconnected) {
        logger.info(
          `[contractor-bridge] dropped queued request sessionKey=${sessionKey} (client disconnected during queue wait)`,
        );
        return;
      }

      // Look up the session-map entry NOW (at the head of the queue), not
      // earlier — the previous turn on the same sessionKey may have just
      // updated `claudeSessionId` and we want to resume into the latest
      // one rather than a stale snapshot from request-arrival time.
      existingEntry = sessionKey ? getSession(workspace, sessionKey) : null;

      // Detect a fresh OpenClaw session even when the bare-reset marker is
      // absent. The marker only arrives when `/new` is the body of *this*
      // user turn (see get-reply isBareSessionReset). When `/new` is sent
      // as a separate slash command (e.g. via Discord's slash UI), OpenClaw
      // processes the reset in a side lane that doesn't hit the bridge —
      // it just renames the prior session file aside. The follow-up real
      // message then arrives on a brand-new OpenClaw session, but as a
      // normal turn with no marker. Without this check, the bridge happily
      // resumes the long-stale claudeSessionId from before the reset.
      //
      // OpenClaw sends the full conversation history every turn (system +
      // user/assistant pairs + latest user). A request with zero assistant
      // turns is therefore a positive signal that the OpenClaw session is
      // brand-new and any prior claudeSessionId we hold is from a previous
      // OpenClaw session that the user already abandoned.
      const hasAssistantHistory = body.messages.some((m) => {
        if (m.role !== "assistant") return false;
        if (typeof m.content === "string") return m.content.trim().length > 0;
        return m.content.some(
          (c) => c.type === "text" && (c.text ?? "").trim().length > 0,
        );
      });
      const isFreshOpenClawSession = !hasAssistantHistory;

      if ((bareSessionReset || isFreshOpenClawSession) && existingEntry && sessionKey) {
        const reason = bareSessionReset
          ? "bare /new detected"
          : "fresh OpenClaw session (no assistant history in messages[])";
        logger.info(
          `[contractor-bridge] ${reason} — dropping prior CLI session sessionKey=${sessionKey} prevClaudeSessionId=${existingEntry.claudeSessionId}`,
        );
        removeSession(workspace, sessionKey);
        existingEntry = null;
      }
      const resumeSessionId =
        existingEntry?.state === "active" ? existingEntry.claudeSessionId : null;

      // Bootstrap is passed as the system prompt on every turn (stateless — not persisted in session files).
      // For Claude: --append-system-prompt appends to the built-in prompt each invocation.
      // For Gemini: written to workspace/GEMINI.md, read dynamically by Gemini CLI each turn.
      // This keeps persona and skills current without needing to track first-turn state.
      const systemPrompt = buildBootstrap({
        agentId,
        openclawSessionKey: sessionKey,
        workspace,
        skillsBlock: skillsBlock || undefined,
        workspaceContextFiles,
      });

      const openclawTools = body.tools ?? [];

      const dispatchIter = isGemini
        ? dispatchToGemini({
            prompt: dispatchPrompt,
            systemPrompt,
            workspace,
            agentId,
            resumeSessionId: resumeSessionId ?? undefined,
            openclawTools,
            bridgePort: port,
            bridgeApiKey: apiKey,
            signal: abortController.signal,
          })
        : dispatchToClaude({
            prompt: dispatchPrompt,
            systemPrompt,
            workspace,
            agentId,
            resumeSessionId: resumeSessionId ?? undefined,
            permissionMode,
            openclawTools,
            bridgePort: port,
            bridgeApiKey: apiKey,
            signal: abortController.signal,
          });

      try {
        for await (const event of dispatchIter) {
          if (event.type === "text") {
            if (!clientDisconnected) sseWrite(res, buildChunk(completionId, event.text));
          } else if (event.type === "done") {
            newSessionId = event.sessionId;
          } else if (event.type === "result_error") {
            // CLI signaled a fatal-but-graceful error (context overflow,
            // refusal, billing, etc.) via `is_error: true` on the result
            // event. The text was already streamed via prior `text` events;
            // record the reason so the bridge can drop the session-map entry
            // below.
            logger.warn(
              `[contractor-bridge] ${isGemini ? "gemini" : "claude"} result_error reason=${event.reason} sessionId=${event.sessionId} message=${event.message.substring(0, 200)}`,
            );
            resultErrorReason = event.reason;
            newSessionId = event.sessionId;
          } else if (event.type === "error") {
            logger.warn(`[contractor-bridge] ${isGemini ? "gemini" : "claude"} error: ${event.message}`);
            hasError = true;
            if (!clientDisconnected) {
              sseWrite(res, buildChunk(completionId, `[contractor-bridge error: ${event.message}]`));
            }
          }
        }
      } catch (err) {
        logger.warn(`[contractor-bridge] dispatch error: ${String(err)}`);
        hasError = true;
        if (!clientDisconnected) {
          sseWrite(res, buildChunk(completionId, `[contractor-bridge dispatch failed: ${String(err)}]`));
        }
      }

      if (!clientDisconnected && !res.writableEnded) {
        sseWrite(res, buildStopChunk(completionId));
        sseWrite(res, "[DONE]");
      }

      // Session-map persistence:
      //  - Successful turn → upsert with the latest claudeSessionId so the next
      //    turn can `--resume` into it.
      //  - Terminal CLI error (context overflow etc., reported via result_error)
      //    → drop the entry so the next turn starts fresh instead of resuming
      //    into the same poisoned session and re-erroring.
      //  - Stream/transport error before any sessionId was captured → mark the
      //    prior entry orphaned (existing behavior).
      //  - Aborted (client disconnected) → don't touch the session-map; the
      //    subprocess may have already updated its own session file on disk,
      //    and the next turn will resume from whatever it left there.
      if (clientDisconnected) {
        // No-op: aborted turn; preserve whatever the prior entry was so the
        // next turn (likely an OpenClaw retry of the same prompt) can resume.
      } else if (resultErrorReason && sessionKey) {
        logger.info(
          `[contractor-bridge] dropping CLI session after terminal error sessionKey=${sessionKey} reason=${resultErrorReason}`,
        );
        removeSession(workspace, sessionKey);
      } else if (newSessionId && sessionKey && !hasError) {
        const now = new Date().toISOString();
        putSession(workspace, {
          openclawSessionKey: sessionKey,
          agentId,
          contractor: isGemini ? "gemini" : "claude",
          claudeSessionId: newSessionId,
          workspace,
          createdAt: existingEntry?.createdAt ?? now,
          lastActivityAt: now,
          state: "active",
        });
        logger.info(
          `[contractor-bridge] session mapped sessionKey=${sessionKey} contractor=${isGemini ? "gemini" : "claude"} sessionId=${newSessionId}`,
        );
      } else if (hasError && sessionKey && existingEntry) {
        markOrphaned(workspace, sessionKey);
      }
    } finally {
      clearInterval(heartbeat);
      req.off("close", onClose);

      // Release our slot so the next request on this sessionKey can proceed.
      // Must happen even on abort/throw, otherwise the chain stalls forever.
      releaseSlot();

      // Garbage-collect the queue entry if no later request chained on us.
      // The Map identity check is the only safe way to tell — newer requests
      // overwrite the entry with their own chain tail.
      if (sessionKey && queueBySession.get(sessionKey) === myChainTail) {
        queueBySession.delete(sessionKey);
      }

      if (!res.writableEnded) {
        try {
          res.end();
        } catch {
          /* ignore */
        }
      }
    }
  }

  const server = http.createServer(async (req, res) => {
    const url = req.url ?? "/";
    const method = req.method ?? "GET";

    // Auth check
    if (apiKey) {
      const auth = req.headers.authorization ?? "";
      if (auth !== `Bearer ${apiKey}`) {
        sendJson(res, 401, { error: "unauthorized" });
        return;
      }
    }

    if (method === "GET" && url === "/health") {
      sendJson(res, 200, { ok: true, service: "contractor-bridge" });
      return;
    }

    if (method === "GET" && url === "/v1/models") {
      sendJson(res, 200, {
        object: "list",
        data: [
          {
            id: "contractor-claude-bridge",
            object: "model",
            created: Math.floor(Date.now() / 1000),
            owned_by: "contractor-agent",
          },
          {
            id: "contractor-gemini-bridge",
            object: "model",
            created: Math.floor(Date.now() / 1000),
            owned_by: "contractor-agent",
          },
        ],
      });
      return;
    }

    if (method === "POST" && url === "/v1/chat/completions") {
      try {
        await handleChatCompletions(req, res);
      } catch (err) {
        logger.warn(`[contractor-bridge] unhandled error: ${String(err)}`);
        if (!res.headersSent) {
          sendJson(res, 500, { error: "internal server error" });
        }
      }
      return;
    }

    // Debug: list registered tools in the global plugin registry
    if (method === "GET" && url === "/debug/tools") {
      const pluginRegistry = getGlobalPluginRegistry();
      const liveConfig = _G["_contractorOpenClawConfig"] ?? null;
      if (!pluginRegistry) {
        sendJson(res, 200, { error: "registry not available" });
      } else {
        sendJson(res, 200, {
          configAvailable: liveConfig !== null,
          tools: pluginRegistry.tools.map((t) => ({ names: t.names, pluginId: t.pluginId })),
        });
      }
      return;
    }

    // MCP proxy tool execution callback.
    // Called by services/openclaw-mcp-server.mjs when Claude Code invokes an MCP tool.
    // Relays the call to OpenClaw's actual tool implementation via the global plugin registry.
    if (method === "POST" && url === "/mcp/execute") {
      let body: { tool?: string; args?: Record<string, unknown>; workspace?: string; agentId?: string };
      try {
        body = await parseBodyRaw(req) as { tool?: string; args?: Record<string, unknown>; workspace?: string; agentId?: string };
      } catch {
        sendJson(res, 400, { error: "invalid_json" });
        return;
      }
      const toolName = body.tool ?? "";
      const toolArgs = body.args ?? {};
      const execWorkspace = body.workspace ?? "";
      const execAgentId = body.agentId ?? "";
      logger.info(`[contractor-bridge] mcp/execute tool=${toolName} workspace=${execWorkspace} agentId=${execAgentId}`);

      // Relay to OpenClaw's actual tool implementation via the global plugin registry.
      // This avoids reimplementing tool logic in the bridge — we call the real tool factory.
      try {
        const pluginRegistry = getGlobalPluginRegistry();
        if (!pluginRegistry) {
          sendJson(res, 200, { error: `[mcp/execute] plugin registry not available (tool=${toolName})` });
          return;
        }

        // Build tool execution context (needed before tool lookup for factory instantiation).
        const liveConfig = (_G["_contractorOpenClawConfig"] ?? null) as Record<string, unknown> | null;
        const canonicalSessionKey = execAgentId ? `agent:${execAgentId}:direct:bridge` : undefined;
        const toolCtx = {
          config: liveConfig ?? undefined,
          workspaceDir: execWorkspace || undefined,
          agentDir: execWorkspace || undefined,
          agentId: execAgentId || undefined,
          sessionKey: canonicalSessionKey,
        };

        // Find tool by name. Some plugins register tools via factory functions without
        // declaring names upfront (names array is empty). For those, instantiate the
        // factory and match by the returned tool's .name property.
        let toolReg = pluginRegistry.tools.find((t) => t.names.includes(toolName));
        if (!toolReg) {
          for (const candidate of pluginRegistry.tools) {
            if (candidate.names.length > 0) continue;
            try {
              const inst = candidate.factory(toolCtx);
              const items = Array.isArray(inst) ? inst : [inst];
              if (items.some((t) => (t as { name?: string }).name === toolName)) {
                toolReg = candidate;
                break;
              }
            } catch { /* skip */ }
          }
        }
        if (!toolReg) {
          sendJson(res, 200, { error: `Tool '${toolName}' not registered in OpenClaw plugin registry` });
          return;
        }

        // Instantiate the tool via its factory
        const toolOrTools = toolReg.factory(toolCtx);
        const toolInstance = Array.isArray(toolOrTools)
          ? toolOrTools.find((t) => (t as { name?: string }).name === toolName)
          : toolOrTools;

        if (!toolInstance || typeof (toolInstance as { execute?: unknown }).execute !== "function") {
          sendJson(res, 200, { error: `Tool '${toolName}' factory returned no executable tool` });
          return;
        }

        const execFn = (toolInstance as { execute: (id: string, args: unknown) => Promise<{ content?: Array<{ type: string; text?: string }> }> }).execute;
        const toolResult = await execFn(randomUUID(), toolArgs);

        // Extract text content from AgentToolResult
        const text = (toolResult.content ?? [])
          .filter((c) => c.type === "text" && c.text)
          .map((c) => c.text as string)
          .join("\n");

        sendJson(res, 200, { result: text || "(no result)" });
      } catch (err) {
        logger.warn(`[contractor-bridge] mcp/execute error tool=${toolName}: ${String(err)}`);
        sendJson(res, 200, { error: `Tool execution failed: ${String(err)}` });
      }
      return;
    }

    sendJson(res, 404, { error: "not_found" });
  });

  server.listen(port, "127.0.0.1", () => {
    logger.info(`[contractor-bridge] sidecar listening on 127.0.0.1:${port}`);
  });

  return server;
}