import { spawn, type ChildProcess } from "child_process"
import { app } from "electron"
import { createRequire } from "module"
import { EventEmitter } from "events"
import { existsSync, readFileSync } from "fs"
import os from "os"
import path from "path"
import { buildUserShellCommand, getUserShellEnv, supportsUserShell } from "./user-shell"

const nodeRequire = createRequire(import.meta.url)


type CliState = "starting" | "ready" | "error" | "stopped"
type ListeningMode = "local" | "all"

export interface CliStatus {
  state: CliState
  pid?: number
  port?: number
  url?: string
  error?: string
}

export interface CliLogEntry {
  stream: "stdout" | "stderr"
  message: string
}

interface StartOptions {
  dev: boolean
}

interface CliEntryResolution {
  entry: string
  runner: "node" | "tsx"
  runnerPath?: string
}

const DEFAULT_CONFIG_PATH = "~/.config/codenomad/config.json"

function resolveConfigPath(configPath?: string): string {
  const target = configPath && configPath.trim().length > 0 ? configPath : DEFAULT_CONFIG_PATH
  if (target.startsWith("~/")) {
    return path.join(os.homedir(), target.slice(2))
  }
  return path.resolve(target)
}

function resolveHostForMode(mode: ListeningMode): string {
  return mode === "local" ? "127.0.0.1" : "0.0.0.0"
}

function readListeningModeFromConfig(): ListeningMode {
  try {
    const configPath = resolveConfigPath(process.env.CLI_CONFIG)
    if (!existsSync(configPath)) return "local"
    const content = readFileSync(configPath, "utf-8")
    const parsed = JSON.parse(content)
    const mode = parsed?.preferences?.listeningMode
    if (mode === "local" || mode === "all") {
      return mode
    }
  } catch (error) {
    console.warn("[cli] failed to read listening mode from config", error)
  }
  return "local"
}

export declare interface CliProcessManager {
  on(event: "status", listener: (status: CliStatus) => void): this
  on(event: "ready", listener: (status: CliStatus) => void): this
  on(event: "log", listener: (entry: CliLogEntry) => void): this
  on(event: "exit", listener: (status: CliStatus) => void): this
  on(event: "error", listener: (error: Error) => void): this
}

export class CliProcessManager extends EventEmitter {
  private child?: ChildProcess
  private status: CliStatus = { state: "stopped" }
  private stdoutBuffer = ""
  private stderrBuffer = ""
  private userEnv: Record<string, string> = {}

  setUserEnv(env: Record<string, string>) {
    this.userEnv = { ...env }
  }

  async start(options: StartOptions): Promise<CliStatus> {
    if (this.child) {
      await this.stop()
    }

    this.stdoutBuffer = ""
    this.stderrBuffer = ""
    this.updateStatus({ state: "starting", port: undefined, pid: undefined, url: undefined, error: undefined })

    const cliEntry = this.resolveCliEntry(options)
    const listeningMode = this.resolveListeningMode()
    const host = resolveHostForMode(listeningMode)
    const args = this.buildCliArgs(options, host)

    console.info(
      `[cli] launching CodeNomad CLI (${options.dev ? "dev" : "prod"}) using ${cliEntry.runner} at ${cliEntry.entry} (host=${host})`,
    )

    const env = supportsUserShell() ? getUserShellEnv() : { ...process.env }
    env.ELECTRON_RUN_AS_NODE = "1"
    Object.assign(env, this.userEnv)

    const spawnDetails = supportsUserShell()
      ? buildUserShellCommand(`ELECTRON_RUN_AS_NODE=1 exec ${this.buildCommand(cliEntry, args)}`)
      : this.buildDirectSpawn(cliEntry, args)

    const child = spawn(spawnDetails.command, spawnDetails.args, {
      cwd: process.cwd(),
      stdio: ["ignore", "pipe", "pipe"],
      env,
      shell: false,
    })

    console.info(`[cli] spawn command: ${spawnDetails.command} ${spawnDetails.args.join(" ")}`)
    if (!child.pid) {
      console.error("[cli] spawn failed: no pid")
    }

    this.child = child
    this.updateStatus({ pid: child.pid ?? undefined })

    child.stdout?.on("data", (data: Buffer) => {
      this.handleStream(data.toString(), "stdout")
    })

    child.stderr?.on("data", (data: Buffer) => {
      this.handleStream(data.toString(), "stderr")
    })

    child.on("error", (error) => {
      console.error("[cli] failed to start CLI:", error)
      this.updateStatus({ state: "error", error: error.message })
      this.emit("error", error)
    })

    child.on("exit", (code, signal) => {
      const failed = this.status.state !== "ready"
      const error = failed ? this.status.error ?? `CLI exited with code ${code ?? 0}${signal ? ` (${signal})` : ""}` : undefined
      console.info(`[cli] exit (code=${code}, signal=${signal || ""})${error ? ` error=${error}` : ""}`)
      this.updateStatus({ state: failed ? "error" : "stopped", error })
      if (failed && error) {
        this.emit("error", new Error(error))
      }
      this.emit("exit", this.status)
      this.child = undefined
    })

    return new Promise<CliStatus>((resolve, reject) => {
      const timeout = setTimeout(() => {
        this.handleTimeout()
        reject(new Error("CLI startup timeout"))
      }, 60000)

      this.once("ready", (status) => {
        clearTimeout(timeout)
        resolve(status)
      })

      this.once("error", (error) => {
        clearTimeout(timeout)
        reject(error)
      })
    })
  }

  async stop(): Promise<void> {
    const child = this.child
    if (!child) {
      this.updateStatus({ state: "stopped" })
      return
    }

    return new Promise((resolve) => {
      const killTimeout = setTimeout(() => {
        child.kill("SIGKILL")
      }, 4000)

      child.on("exit", () => {
        clearTimeout(killTimeout)
        this.child = undefined
        console.info("[cli] CLI process exited")
        this.updateStatus({ state: "stopped" })
        resolve()
      })

      child.kill("SIGTERM")
    })
  }

  getStatus(): CliStatus {
    return { ...this.status }
  }

  private resolveListeningMode(): ListeningMode {
    return readListeningModeFromConfig()
  }

  private handleTimeout() {
    if (this.child) {
      this.child.kill("SIGKILL")
      this.child = undefined
    }
    this.updateStatus({ state: "error", error: "CLI did not start in time" })
    this.emit("error", new Error("CLI did not start in time"))
  }

  private handleStream(chunk: string, stream: "stdout" | "stderr") {
    if (stream === "stdout") {
      this.stdoutBuffer += chunk
      this.processBuffer("stdout")
    } else {
      this.stderrBuffer += chunk
      this.processBuffer("stderr")
    }
  }

  private processBuffer(stream: "stdout" | "stderr") {
    const buffer = stream === "stdout" ? this.stdoutBuffer : this.stderrBuffer
    const lines = buffer.split("\n")
    const trailing = lines.pop() ?? ""

    if (stream === "stdout") {
      this.stdoutBuffer = trailing
    } else {
      this.stderrBuffer = trailing
    }

    for (const line of lines) {
      if (!line.trim()) continue
      console.info(`[cli][${stream}] ${line}`)
      this.emit("log", { stream, message: line })

      const port = this.extractPort(line)
      if (port && this.status.state === "starting") {
        const url = `http://127.0.0.1:${port}`
        console.info(`[cli] ready on ${url}`)
        this.updateStatus({ state: "ready", port, url })
        this.emit("ready", this.status)
      }
    }
  }

  private extractPort(line: string): number | null {
    const readyMatch = line.match(/CodeNomad Server is ready at http:\/\/[^:]+:(\d+)/i)
    if (readyMatch) {
      return parseInt(readyMatch[1], 10)
    }

    if (line.toLowerCase().includes("http server listening")) {
      const httpMatch = line.match(/:(\d{2,5})(?!.*:\d)/)
      if (httpMatch) {
        return parseInt(httpMatch[1], 10)
      }
      try {
        const parsed = JSON.parse(line)
        if (typeof parsed.port === "number") {
          return parsed.port
        }
      } catch {
        // not JSON, ignore
      }
    }

    return null
  }

  private updateStatus(patch: Partial<CliStatus>) {
    this.status = { ...this.status, ...patch }
    this.emit("status", this.status)
  }

  private buildCliArgs(options: StartOptions, host: string): string[] {
    const args = ["serve", "--host", host, "--port", "0"]

    if (options.dev) {
      const uiPort = process.env.VITE_PORT || "3000"
      args.push("--ui-dev-server", `http://localhost:${uiPort}`, "--log-level", "debug")
    }

    return args
  }

  private buildCommand(cliEntry: CliEntryResolution, args: string[]): string {
    const parts = [JSON.stringify(process.execPath)]
    if (cliEntry.runner === "tsx" && cliEntry.runnerPath) {
      parts.push(JSON.stringify(cliEntry.runnerPath))
    }
    parts.push(JSON.stringify(cliEntry.entry))
    args.forEach((arg) => parts.push(JSON.stringify(arg)))
    return parts.join(" ")
  }

  private buildDirectSpawn(cliEntry: CliEntryResolution, args: string[]) {
    if (cliEntry.runner === "tsx") {
      return { command: process.execPath, args: [cliEntry.runnerPath!, cliEntry.entry, ...args] }
    }

    return { command: process.execPath, args: [cliEntry.entry, ...args] }
  }

  private resolveCliEntry(options: StartOptions): CliEntryResolution {
    if (options.dev) {
      const tsxPath = this.resolveTsx()
      if (!tsxPath) {
        throw new Error("tsx is required to run the CLI in development mode. Please install dependencies.")
      }
      const devEntry = this.resolveDevEntry()
      return { entry: devEntry, runner: "tsx", runnerPath: tsxPath }
    }
 
    const distEntry = this.resolveProdEntry()
    return { entry: distEntry, runner: "node" }
  }
 
  private resolveTsx(): string | null {
    const candidates: Array<string | (() => string)> = [
      () => nodeRequire.resolve("tsx/cli"),
      () => nodeRequire.resolve("tsx/dist/cli.mjs"),
      () => nodeRequire.resolve("tsx/dist/cli.cjs"),
      path.resolve(process.cwd(), "node_modules", "tsx", "dist", "cli.mjs"),
      path.resolve(process.cwd(), "node_modules", "tsx", "dist", "cli.cjs"),
      path.resolve(process.cwd(), "..", "node_modules", "tsx", "dist", "cli.mjs"),
      path.resolve(process.cwd(), "..", "node_modules", "tsx", "dist", "cli.cjs"),
      path.resolve(process.cwd(), "..", "..", "node_modules", "tsx", "dist", "cli.mjs"),
      path.resolve(process.cwd(), "..", "..", "node_modules", "tsx", "dist", "cli.cjs"),
      path.resolve(app.getAppPath(), "..", "node_modules", "tsx", "dist", "cli.mjs"),
      path.resolve(app.getAppPath(), "..", "node_modules", "tsx", "dist", "cli.cjs"),
    ]
 
    for (const candidate of candidates) {
      try {
        const resolved = typeof candidate === "function" ? candidate() : candidate
        if (resolved && existsSync(resolved)) {
          return resolved
        }
      } catch {
        continue
      }
    }
 
    return null
  }
 
  private resolveDevEntry(): string {
    const entry = path.resolve(process.cwd(), "..", "server", "src", "index.ts")
    if (!existsSync(entry)) {
      throw new Error(`Dev CLI entry not found at ${entry}. Run npm run dev:electron from the repository root after installing dependencies.`)
    }
    return entry
  }
 
  private resolveProdEntry(): string {
    try {
      const entry = nodeRequire.resolve("@neuralnomads/codenomad/dist/bin.js")
      if (existsSync(entry)) {
        return entry
      }
    } catch {
      // fall through to error below
    }
    throw new Error("Unable to locate CodeNomad CLI build (dist/bin.js). Run npm run build --workspace @neuralnomads/codenomad.")
  }
}