import { createOpencode } from "@opencode-ai/sdk"
import pc from "picocolors"
import type { RunOptions, RunContext } from "./types"
import { checkCompletionConditions } from "./completion"
import { createEventState, processEvents, serializeError } from "./events"
import type { OhMyOpenCodeConfig } from "../../config"
import { loadPluginConfig } from "../../plugin-config"
import { getAvailableServerPort, DEFAULT_SERVER_PORT } from "../../shared/port-utils"

const POLL_INTERVAL_MS = 500
const DEFAULT_TIMEOUT_MS = 0
const SESSION_CREATE_MAX_RETRIES = 3
const SESSION_CREATE_RETRY_DELAY_MS = 1000
const CORE_AGENT_ORDER = ["sisyphus", "hephaestus", "prometheus", "atlas"] as const
const DEFAULT_AGENT = "sisyphus"

type EnvVars = Record<string, string | undefined>

const normalizeAgentName = (agent?: string): string | undefined => {
  if (!agent) return undefined
  const trimmed = agent.trim()
  if (!trimmed) return undefined
  const lowered = trimmed.toLowerCase()
  const coreMatch = CORE_AGENT_ORDER.find((name) => name.toLowerCase() === lowered)
  return coreMatch ?? trimmed
}

const isAgentDisabled = (agent: string, config: OhMyOpenCodeConfig): boolean => {
  const lowered = agent.toLowerCase()
  if (lowered === "sisyphus" && config.sisyphus_agent?.disabled === true) {
    return true
  }
  return (config.disabled_agents ?? []).some(
    (disabled) => disabled.toLowerCase() === lowered
  )
}

const pickFallbackAgent = (config: OhMyOpenCodeConfig): string => {
  for (const agent of CORE_AGENT_ORDER) {
    if (!isAgentDisabled(agent, config)) {
      return agent
    }
  }
  return DEFAULT_AGENT
}

export const resolveRunAgent = (
  options: RunOptions,
  pluginConfig: OhMyOpenCodeConfig,
  env: EnvVars = process.env
): string => {
  const cliAgent = normalizeAgentName(options.agent)
  const envAgent = normalizeAgentName(env.OPENCODE_DEFAULT_AGENT)
  const configAgent = normalizeAgentName(pluginConfig.default_run_agent)
  const resolved = cliAgent ?? envAgent ?? configAgent ?? DEFAULT_AGENT
  const normalized = normalizeAgentName(resolved) ?? DEFAULT_AGENT

  if (isAgentDisabled(normalized, pluginConfig)) {
    const fallback = pickFallbackAgent(pluginConfig)
    const fallbackDisabled = isAgentDisabled(fallback, pluginConfig)
    if (fallbackDisabled) {
      console.log(
        pc.yellow(
          `Requested agent "${normalized}" is disabled and no enabled core agent was found. Proceeding with "${fallback}".`
        )
      )
      return fallback
    }
    console.log(
      pc.yellow(
        `Requested agent "${normalized}" is disabled. Falling back to "${fallback}".`
      )
    )
    return fallback
  }

  return normalized
}

export async function run(options: RunOptions): Promise<number> {
  // Set CLI run mode environment variable before any config loading
  // This signals to config-handler to deny Question tool (no TUI to answer)
  process.env.OPENCODE_CLI_RUN_MODE = "true"

  const {
    message,
    directory = process.cwd(),
    timeout = DEFAULT_TIMEOUT_MS,
  } = options
  const pluginConfig = loadPluginConfig(directory, { command: "run" })
  const resolvedAgent = resolveRunAgent(options, pluginConfig)

  console.log(pc.cyan("Starting opencode server (auto port selection enabled)..."))

  const abortController = new AbortController()
  let timeoutId: ReturnType<typeof setTimeout> | null = null

  // timeout=0 means no timeout (run until completion)
  if (timeout > 0) {
    timeoutId = setTimeout(() => {
      console.log(pc.yellow("\nTimeout reached. Aborting..."))
      abortController.abort()
    }, timeout)
  }

  try {
    const envPort = process.env.OPENCODE_SERVER_PORT
      ? parseInt(process.env.OPENCODE_SERVER_PORT, 10)
      : undefined
    const serverHostname = process.env.OPENCODE_SERVER_HOSTNAME || "127.0.0.1"
    const preferredPort = envPort && !isNaN(envPort) ? envPort : DEFAULT_SERVER_PORT

    const { port: serverPort, wasAutoSelected } = await getAvailableServerPort(preferredPort, serverHostname)

    if (wasAutoSelected) {
      console.log(pc.yellow(`Port ${preferredPort} is busy, using port ${serverPort} instead`))
    } else {
      console.log(pc.dim(`Using port ${serverPort}`))
    }

    const { client, server } = await createOpencode({
      signal: abortController.signal,
      port: serverPort,
      hostname: serverHostname,
    })

    const cleanup = () => {
      if (timeoutId) clearTimeout(timeoutId)
      server.close()
    }

    process.on("SIGINT", () => {
      console.log(pc.yellow("\nInterrupted. Shutting down..."))
      cleanup()
      process.exit(130)
    })

    try {
      // Retry session creation with exponential backoff
      // Server might not be fully ready even after "listening" message
      let sessionID: string | undefined
      let lastError: unknown

      for (let attempt = 1; attempt <= SESSION_CREATE_MAX_RETRIES; attempt++) {
        const sessionRes = await client.session.create({
          body: { title: "oh-my-opencode run" },
        })

        if (sessionRes.error) {
          lastError = sessionRes.error
          console.error(pc.yellow(`Session create attempt ${attempt}/${SESSION_CREATE_MAX_RETRIES} failed:`))
          console.error(pc.dim(`  Error: ${serializeError(sessionRes.error)}`))

          if (attempt < SESSION_CREATE_MAX_RETRIES) {
            const delay = SESSION_CREATE_RETRY_DELAY_MS * attempt
            console.log(pc.dim(`  Retrying in ${delay}ms...`))
            await new Promise((resolve) => setTimeout(resolve, delay))
            continue
          }
        }

        sessionID = sessionRes.data?.id
        if (sessionID) {
          break
        }

        // No error but also no session ID - unexpected response
        lastError = new Error(`Unexpected response: ${JSON.stringify(sessionRes, null, 2)}`)
        console.error(pc.yellow(`Session create attempt ${attempt}/${SESSION_CREATE_MAX_RETRIES}: No session ID returned`))

        if (attempt < SESSION_CREATE_MAX_RETRIES) {
          const delay = SESSION_CREATE_RETRY_DELAY_MS * attempt
          console.log(pc.dim(`  Retrying in ${delay}ms...`))
          await new Promise((resolve) => setTimeout(resolve, delay))
        }
      }

      if (!sessionID) {
        console.error(pc.red("Failed to create session after all retries"))
        console.error(pc.dim(`Last error: ${serializeError(lastError)}`))
        cleanup()
        return 1
      }

      console.log(pc.dim(`Session: ${sessionID}`))

      const ctx: RunContext = {
        client,
        sessionID,
        directory,
        abortController,
      }

      const events = await client.event.subscribe()
      const eventState = createEventState()
      const eventProcessor = processEvents(ctx, events.stream, eventState)

      console.log(pc.dim("\nSending prompt..."))
      await client.session.promptAsync({
        path: { id: sessionID },
        body: {
          agent: resolvedAgent,
          parts: [{ type: "text", text: message }],
        },
        query: { directory },
      })

      console.log(pc.dim("Waiting for completion...\n"))

      while (!abortController.signal.aborted) {
        await new Promise((resolve) => setTimeout(resolve, POLL_INTERVAL_MS))

        if (!eventState.mainSessionIdle) {
          continue
        }

        // Check if session errored - exit with failure if so
        if (eventState.mainSessionError) {
          console.error(pc.red(`\n\nSession ended with error: ${eventState.lastError}`))
          console.error(pc.yellow("Check if todos were completed before the error."))
          cleanup()
          process.exit(1)
        }

        // Guard against premature completion: don't check completion until the
        // session has produced meaningful work (text output, tool call, or tool result).
        // Without this, a session that goes busy->idle before the LLM responds
        // would exit immediately because 0 todos + 0 children = "complete".
        if (!eventState.hasReceivedMeaningfulWork) {
          continue
        }

        const shouldExit = await checkCompletionConditions(ctx)
        if (shouldExit) {
          console.log(pc.green("\n\nAll tasks completed."))
          cleanup()
          process.exit(0)
        }
      }

      await eventProcessor.catch(() => {})
      cleanup()
      return 130
    } catch (err) {
      cleanup()
      throw err
    }
  } catch (err) {
    if (timeoutId) clearTimeout(timeoutId)
    if (err instanceof Error && err.name === "AbortError") {
      return 130
    }
    console.error(pc.red(`Error: ${serializeError(err)}`))
    return 1
  }
}