import { spawn } from "node:child_process";
import fs from "node:fs";
import http from "node:http";
import os from "node:os";
import path from "node:path";
import type { Duplex } from "node:stream";

import {
  EDITORS,
  coreDispatchInputSchema,
  coreGetSnapshotInputSchema,
  gitStatusResultSchema,
  WS_CHANNELS,
  WS_METHODS,
  type CoreDispatchInput,
  type CoreViewDelta,
  type TerminalEvent,
  type WsPush,
  type WsRequest,
  type WsResponse,
  wsRequestSchema,
  DEFAULT_MODEL,
} from "@t3tools/contracts";
import { WebSocketServer, type WebSocket } from "ws";

import { createLogger } from "./logger";
import { ProjectRegistry } from "./projectRegistry";
import { ProviderManager } from "./providerManager";
import { GitManager } from "./gitManager";
import {
  checkoutGitBranch,
  createGitBranch,
  createGitWorktree,
  initGitRepo,
  listGitBranches,
  pullGitBranch,
  removeGitWorktree,
} from "./git";
import { TerminalManager } from "./terminalManager";
import { loadResolvedKeybindingsConfig, upsertKeybindingRule } from "./keybindings";
import { searchWorkspaceEntries } from "./workspaceEntries";
import { CoreEngine } from "./effect/coreEngine";
import { SqliteEventStore } from "./effect/eventStore";

const MIME_TYPES: Record<string, string> = {
  ".html": "text/html; charset=utf-8",
  ".js": "application/javascript; charset=utf-8",
  ".css": "text/css; charset=utf-8",
  ".json": "application/json; charset=utf-8",
  ".png": "image/png",
  ".jpg": "image/jpeg",
  ".svg": "image/svg+xml",
  ".ico": "image/x-icon",
  ".woff": "font/woff",
  ".woff2": "font/woff2",
  ".ttf": "font/ttf",
  ".map": "application/json",
};

export interface ServerOptions {
  port: number;
  host?: string | undefined;
  cwd: string;
  stateDir?: string | undefined;
  staticDir?: string | undefined;
  devUrl?: string | undefined;
  logWebSocketEvents?: boolean | undefined;
  projectRegistry?: ProjectRegistry | undefined;
  gitManager?: GitManager | undefined;
  terminalManager?: TerminalManager | undefined;
  authToken?: string | undefined;
}

function parseBooleanEnv(value: string | undefined): boolean | undefined {
  if (value === undefined) return undefined;
  const normalized = value.trim().toLowerCase();
  if (["1", "true", "yes", "on"].includes(normalized)) return true;
  if (["0", "false", "no", "off"].includes(normalized)) return false;
  return undefined;
}

export function createServer(options: ServerOptions) {
  const {
    port,
    host,
    cwd,
    stateDir,
    staticDir,
    devUrl,
    logWebSocketEvents: explicitLogWsEvents,
    projectRegistry: providedRegistry,
    gitManager: providedGitManager,
    terminalManager: providedTerminalManager,
    authToken,
  } = options;
  const providerManager = new ProviderManager();
  const terminalManager = providedTerminalManager ?? new TerminalManager();
  const projectRegistry =
    providedRegistry ?? new ProjectRegistry(path.join(os.homedir(), ".t3", "userdata"));
  const gitManager = providedGitManager ?? new GitManager();
  const eventStore = new SqliteEventStore(
    path.join(stateDir ?? path.join(os.homedir(), ".t3", "userdata"), "event-core.sqlite"),
  );
  const coreEngine = new CoreEngine({
    eventStore,
    probeGitStatus: async (probeCwd) => {
      const status = await gitManager.status({ cwd: probeCwd });
      const parsed = gitStatusResultSchema.parse(status);
      return {
        cwd: probeCwd,
        branch: parsed.branch,
        hasWorkingTreeChanges: parsed.hasWorkingTreeChanges,
        aheadCount: parsed.aheadCount,
        behindCount: parsed.behindCount,
        observedAt: new Date().toISOString(),
      };
    },
  });
  const clients = new Set<WebSocket>();
  const logger = createLogger("ws");
  const logWebSocketEvents =
    explicitLogWsEvents ?? parseBooleanEnv(process.env.T3CODE_LOG_WS_EVENTS) ?? Boolean(devUrl);
  let keybindingsConfig = loadResolvedKeybindingsConfig(logger);

  function logOutgoingPush(push: WsPush, recipients: number) {
    if (!logWebSocketEvents) return;
    logger.event("outgoing push", {
      channel: push.channel,
      recipients,
      payload: push.data,
    });
  }

  function broadcastPush(push: WsPush): void {
    const message = JSON.stringify(push);
    let recipients = 0;
    for (const client of clients) {
      if (client.readyState === client.OPEN) {
        client.send(message);
        recipients += 1;
      }
    }
    logOutgoingPush(push, recipients);
  }

  // Forward provider events to all connected WebSocket clients
  providerManager.on("event", (event) => {
    const push: WsPush = {
      type: "push",
      channel: WS_CHANNELS.providerEvent,
      data: event,
    };
    broadcastPush(push);
    if (
      event.threadId &&
      typeof event.message === "string" &&
      event.message.trim().length > 0 &&
      (event.kind === "notification" || event.method === "turn/completed")
    ) {
      void coreEngine.dispatch({
        command: {
          kind: "AppendAssistantMessage",
          commandId: crypto.randomUUID(),
          issuedAt: new Date().toISOString(),
          payload: {
            threadId: event.threadId,
            messageId: event.itemId ?? crypto.randomUUID(),
            text: event.message,
            createdAt: event.createdAt,
          },
        },
      });
    }
  });

  const onTerminalEvent = (event: TerminalEvent) => {
    const push: WsPush = {
      type: "push",
      channel: WS_CHANNELS.terminalEvent,
      data: event,
    };
    broadcastPush(push);
  };
  terminalManager.on("event", onTerminalEvent);

  let unsubscribeCoreDelta: (() => void) | null = null;

  // HTTP server — serves static files or redirects to Vite dev server
  const httpServer = http.createServer((req, res) => {
    // In dev mode, redirect to Vite dev server
    if (devUrl) {
      res.writeHead(302, { Location: devUrl });
      res.end();
      return;
    }

    // Serve static files from the web app build
    if (!staticDir) {
      res.writeHead(503, { "Content-Type": "text/plain" });
      res.end("No static directory configured and no dev URL set.");
      return;
    }

    const url = new URL(req.url ?? "/", `http://localhost:${port}`);
    let filePath = path.join(staticDir, url.pathname);

    // SPA fallback: if no file extension and not found, serve index.html
    const ext = path.extname(filePath);
    if (!ext) {
      filePath = path.join(filePath, "index.html");
    }

    fs.stat(filePath, (err, stats) => {
      if (err || !stats?.isFile()) {
        // SPA fallback
        const indexPath = path.join(staticDir, "index.html");
        fs.readFile(indexPath, (readErr, data) => {
          if (readErr) {
            res.writeHead(404, { "Content-Type": "text/plain" });
            res.end("Not Found");
            return;
          }
          res.writeHead(200, { "Content-Type": "text/html; charset=utf-8" });
          res.end(data);
        });
        return;
      }

      const fileExt = path.extname(filePath);
      const contentType = MIME_TYPES[fileExt] ?? "application/octet-stream";

      fs.readFile(filePath, (readErr, data) => {
        if (readErr) {
          res.writeHead(500, { "Content-Type": "text/plain" });
          res.end("Internal Server Error");
          return;
        }
        res.writeHead(200, { "Content-Type": contentType });
        res.end(data);
      });
    });
  });

  // WebSocket server — upgrades from the HTTP server
  const wss = new WebSocketServer({ noServer: true });

  function rejectUpgrade(socket: Duplex, statusCode: number, message: string): void {
    socket.write(
      `HTTP/1.1 ${statusCode} ${statusCode === 401 ? "Unauthorized" : "Bad Request"}\r\n` +
        "Connection: close\r\n" +
        "Content-Type: text/plain\r\n" +
        `Content-Length: ${Buffer.byteLength(message)}\r\n` +
        "\r\n" +
        message,
    );
    socket.destroy();
  }

  httpServer.on("upgrade", (request, socket, head) => {
    if (authToken) {
      let providedToken: string | null = null;
      try {
        const url = new URL(request.url ?? "/", `http://localhost:${port}`);
        providedToken = url.searchParams.get("token");
      } catch {
        rejectUpgrade(socket, 400, "Invalid WebSocket URL");
        return;
      }

      if (providedToken !== authToken) {
        rejectUpgrade(socket, 401, "Unauthorized WebSocket connection");
        return;
      }
    }

    wss.handleUpgrade(request, socket, head, (ws) => {
      wss.emit("connection", ws, request);
    });
  });

  wss.on("connection", (ws) => {
    clients.add(ws);

    // Send welcome message with project info
    const segments = cwd.split(/[/\\]/).filter(Boolean);
    const projectName = segments[segments.length - 1] ?? "project";

    const welcome: WsPush = {
      type: "push",
      channel: WS_CHANNELS.serverWelcome,
      data: { cwd, projectName },
    };
    logOutgoingPush(welcome, 1);
    ws.send(JSON.stringify(welcome));

    ws.on("message", (raw) => {
      void handleMessage(ws, raw);
    });

    ws.on("close", () => {
      clients.delete(ws);
    });

    ws.on("error", () => {
      clients.delete(ws);
    });
  });

  async function handleMessage(ws: WebSocket, raw: unknown) {
    let request: WsRequest;
    try {
      const parsed = JSON.parse(String(raw));
      request = wsRequestSchema.parse(parsed);
    } catch {
      const errorResponse: WsResponse = {
        id: "unknown",
        error: { message: "Invalid request format" },
      };
      ws.send(JSON.stringify(errorResponse));
      return;
    }

    try {
      const result = await routeRequest(request);
      const response: WsResponse = { id: request.id, result };
      ws.send(JSON.stringify(response));
    } catch (err) {
      const message = err instanceof Error ? err.message : "Unknown server error";
      const response: WsResponse = {
        id: request.id,
        error: { message },
      };
      ws.send(JSON.stringify(response));
    }
  }

  async function routeRequest(request: WsRequest): Promise<unknown> {
    switch (request.method) {
      case WS_METHODS.providersStartSession:
        return providerManager.startSession(request.params as never);

      case WS_METHODS.providersSendTurn:
        return providerManager.sendTurn(request.params as never);

      case WS_METHODS.providersInterruptTurn:
        return providerManager.interruptTurn(request.params as never);

      case WS_METHODS.providersRespondToRequest:
        return providerManager.respondToRequest(request.params as never);

      case WS_METHODS.providersStopSession: {
        providerManager.stopSession(request.params as never);
        return undefined;
      }

      case WS_METHODS.providersListSessions:
        return providerManager.listSessions();

      case WS_METHODS.providersListCheckpoints:
        return providerManager.listCheckpoints(request.params as never);

      case WS_METHODS.providersGetCheckpointDiff:
        return providerManager.getCheckpointDiff(request.params as never);

      case WS_METHODS.providersRevertToCheckpoint:
        return providerManager.revertToCheckpoint(request.params as never);

      case WS_METHODS.projectsList:
        return projectRegistry.list();

      case WS_METHODS.projectsAdd:
        return (async () => {
          const result = projectRegistry.add(request.params as never);
          const command: CoreDispatchInput = {
            command: {
              kind: "CreateProject",
              commandId: crypto.randomUUID(),
              issuedAt: new Date().toISOString(),
              payload: {
                id: result.project.id,
                name: result.project.name,
                cwd: result.project.cwd,
                model: DEFAULT_MODEL,
              },
            },
          };
          await coreEngine.dispatch(command);
          return result;
        })();

      case WS_METHODS.projectsRemove:
        projectRegistry.remove(request.params as never);
        return undefined;

      case WS_METHODS.projectsSearchEntries:
        return searchWorkspaceEntries(request.params as never);
      case WS_METHODS.projectsUpdateScripts:
        return projectRegistry.updateScripts(request.params as never);

      case WS_METHODS.shellOpenInEditor: {
        const params = request.params as {
          cwd: string;
          editor: string;
        };
        if (!params?.cwd) throw new Error("cwd is required");
        const editorDef = EDITORS.find((e) => e.id === params.editor);
        if (!editorDef) throw new Error(`Unknown editor: ${params.editor}`);

        let command: string;
        let args: string[];

        if (editorDef.command) {
          command = editorDef.command;
          args = [params.cwd];
        } else if (editorDef.id === "file-manager") {
          // Use platform-specific file manager command
          switch (process.platform) {
            case "darwin":
              command = "open";
              break;
            case "win32":
              command = "explorer";
              break;
            default:
              command = "xdg-open";
              break;
          }
          args = [params.cwd];
        } else {
          return undefined;
        }

        const child = spawn(command, args, {
          detached: true,
          stdio: "ignore",
        });
        child.on("error", () => {
          /* ignore spawn failures for detached editors */
        });
        child.unref();
        return undefined;
      }

      case WS_METHODS.gitStatus:
        return gitManager.status(request.params as never);

      case WS_METHODS.gitPull:
        return pullGitBranch(request.params as never).then(async (result) => {
          const input = request.params as { cwd: string };
          await coreEngine.dispatch({
            command: {
              kind: "GitWorkflow",
              commandId: crypto.randomUUID(),
              issuedAt: new Date().toISOString(),
              payload: {
                workflow: "stacked_action",
                cwd: input.cwd,
                metadata: { source: "git.pull", result },
              },
            },
          });
          return result;
        });

      case WS_METHODS.gitRunStackedAction:
        return gitManager.runStackedAction(request.params as never).then(async (result) => {
          const input = request.params as { cwd: string; action: string };
          await coreEngine.dispatch({
            command: {
              kind: "GitWorkflow",
              commandId: crypto.randomUUID(),
              issuedAt: new Date().toISOString(),
              payload: {
                workflow: "stacked_action",
                cwd: input.cwd,
                metadata: { source: "git.runStackedAction", action: input.action, result },
              },
            },
          });
          return result;
        });
      case WS_METHODS.gitListBranches:
        return listGitBranches(request.params as never);

      case WS_METHODS.gitCreateWorktree:
        return createGitWorktree(request.params as never).then(async (result) => {
          const input = request.params as { cwd: string; branch: string; newBranch: string };
          await coreEngine.dispatch({
            command: {
              kind: "GitWorkflow",
              commandId: crypto.randomUUID(),
              issuedAt: new Date().toISOString(),
              payload: {
                workflow: "create_worktree",
                cwd: input.cwd,
                metadata: {
                  branch: input.branch,
                  newBranch: input.newBranch,
                  result,
                },
              },
            },
          });
          return result;
        });

      case WS_METHODS.gitRemoveWorktree:
        return removeGitWorktree(request.params as never).then(async () => {
          const input = request.params as { cwd: string; path: string };
          await coreEngine.dispatch({
            command: {
              kind: "GitWorkflow",
              commandId: crypto.randomUUID(),
              issuedAt: new Date().toISOString(),
              payload: {
                workflow: "remove_worktree",
                cwd: input.cwd,
                metadata: { path: input.path },
              },
            },
          });
        });

      case WS_METHODS.gitCreateBranch:
        return createGitBranch(request.params as never).then(async () => {
          const input = request.params as { cwd: string; branch: string };
          await coreEngine.dispatch({
            command: {
              kind: "GitWorkflow",
              commandId: crypto.randomUUID(),
              issuedAt: new Date().toISOString(),
              payload: {
                workflow: "create_branch",
                cwd: input.cwd,
                metadata: { branch: input.branch },
              },
            },
          });
        });

      case WS_METHODS.gitCheckout:
        return checkoutGitBranch(request.params as never).then(async () => {
          const input = request.params as { cwd: string; branch: string };
          await coreEngine.dispatch({
            command: {
              kind: "GitWorkflow",
              commandId: crypto.randomUUID(),
              issuedAt: new Date().toISOString(),
              payload: {
                workflow: "checkout",
                cwd: input.cwd,
                metadata: { branch: input.branch },
              },
            },
          });
        });

      case WS_METHODS.gitInit:
        return initGitRepo(request.params as never).then(async () => {
          const input = request.params as { cwd: string };
          await coreEngine.dispatch({
            command: {
              kind: "GitProbe",
              commandId: crypto.randomUUID(),
              issuedAt: new Date().toISOString(),
              payload: { cwd: input.cwd },
            },
          });
        });

      case WS_METHODS.terminalOpen:
        return terminalManager.open(request.params as never);

      case WS_METHODS.terminalWrite:
        await terminalManager.write(request.params as never);
        return undefined;

      case WS_METHODS.terminalResize:
        await terminalManager.resize(request.params as never);
        return undefined;

      case WS_METHODS.terminalClear:
        await terminalManager.clear(request.params as never);
        return undefined;

      case WS_METHODS.terminalRestart:
        return terminalManager.restart(request.params as never);

      case WS_METHODS.terminalClose:
        await terminalManager.close(request.params as never);
        return undefined;

      case WS_METHODS.serverGetConfig:
        return {
          cwd,
          keybindings: keybindingsConfig,
        };

      case WS_METHODS.serverUpsertKeybinding:
        keybindingsConfig = upsertKeybindingRule(logger, request.params);
        return {
          keybindings: keybindingsConfig,
        };

      case WS_METHODS.coreGetSnapshot:
        coreGetSnapshotInputSchema.parse(request.params ?? {});
        return coreEngine.getSnapshot();

      case WS_METHODS.coreDispatch: {
        const input = coreDispatchInputSchema.parse(request.params);
        return coreEngine.dispatch(input);
      }

      default:
        throw new Error(`Unknown method: ${request.method}`);
    }
  }

  function start() {
    return coreEngine.start().then(
      () =>
        new Promise<void>((resolve, reject) => {
          const onError = (error: Error) => {
            httpServer.off("error", onError);
            reject(error);
          };
          httpServer.once("error", onError);
          const onListening = () => {
            httpServer.off("error", onError);
            unsubscribeCoreDelta = coreEngine.subscribe((delta: CoreViewDelta) => {
              const push: WsPush = {
                type: "push",
                channel: WS_CHANNELS.coreViewDelta,
                data: delta,
              };
              broadcastPush(push);
            });
            resolve();
          };
          if (host) {
            httpServer.listen(port, host, onListening);
            return;
          }
          httpServer.listen(port, onListening);
        }),
    );
  }

  async function stop(): Promise<void> {
    if (unsubscribeCoreDelta) {
      unsubscribeCoreDelta();
      unsubscribeCoreDelta = null;
    }
    terminalManager.off("event", onTerminalEvent);
    providerManager.stopAll();
    providerManager.dispose();
    terminalManager.dispose();
    await coreEngine.stop();
    eventStore.close();

    for (const client of clients) {
      client.close();
    }
    clients.clear();

    const isServerNotRunningError = (error: unknown): boolean => {
      if (!(error instanceof Error)) return false;
      const maybeCode = (error as NodeJS.ErrnoException).code;
      return (
        maybeCode === "ERR_SERVER_NOT_RUNNING" ||
        error.message.toLowerCase().includes("not running")
      );
    };

    const closeWebSocketServer = new Promise<void>((resolve, reject) => {
      wss.close((error) => {
        if (error && !isServerNotRunningError(error)) {
          reject(error);
          return;
        }
        resolve();
      });
    });

    const closeHttpServer = new Promise<void>((resolve, reject) => {
      httpServer.close((error) => {
        if (error && !isServerNotRunningError(error)) {
          reject(error);
          return;
        }
        resolve();
      });
    });

    await Promise.all([closeWebSocketServer, closeHttpServer]);
  }

  return { start, stop, httpServer };
}