{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE NoImplicitPrelude #-}

module Omni.Agent.Worker where

import Alpha
import qualified Data.Text as Text
import qualified Data.Text.IO as TIO
import qualified Omni.Agent.Core as Core
import qualified Omni.Agent.Git as Git
import qualified Omni.Agent.Log as AgentLog
import qualified Omni.Task.Core as TaskCore
import qualified System.Directory as Directory
import qualified System.Exit as Exit
import System.FilePath ((</>))
import qualified System.IO as IO
import qualified System.Process as Process

start :: Core.Worker -> IO ()
start worker = do
  AgentLog.init (Core.workerName worker)
  AgentLog.log ("Worker starting loop for " <> Core.workerName worker)
  loop worker

loop :: Core.Worker -> IO ()
loop worker = do
  let repo = Core.workerPath worker

  AgentLog.updateActivity "Syncing tasks..."
  -- Sync with live first to get latest code and tasks
  -- We ignore errors here to keep the loop alive, but syncWithLive panics on conflict.
  -- Ideally we should catch exceptions, but for now let it fail and restart (via supervisor or manual).
  Git.syncWithLive repo

  -- Sync tasks database (import from live)
  -- Since we rebased, .tasks/tasks.jsonl should be up to date with live.
  -- But we might need to consolidate if there are merge artifacts (not likely with rebase).
  -- The bash script calls ./Omni/Agent/sync-tasks.sh which calls 'task import'.
  -- Here we rely on 'task loadTasks' reading the file.
  -- But 'syncWithLive' already updated the file from git.

  -- Find ready work
  readyTasks <- TaskCore.getReadyTasks
  case readyTasks of
    [] -> do
      AgentLog.updateActivity "No work found, sleeping..."
      threadDelay (60 * 1000000) -- 60 seconds
      loop worker
    (task : _) -> do
      processTask worker task
      loop worker

processTask :: Core.Worker -> TaskCore.Task -> IO ()
processTask worker task = do
  let repo = Core.workerPath worker
  let tid = TaskCore.taskId task

  AgentLog.update (\s -> s {AgentLog.statusTask = Just tid})
  AgentLog.updateActivity ("Claiming task " <> tid)

  -- Claim task
  TaskCore.updateTaskStatus tid TaskCore.InProgress []

  -- Commit claim locally
  Git.commit repo ("task: claim " <> tid)

  -- Prepare branch
  let taskBranch = "task/" <> tid
  currentBranch <- Git.getCurrentBranch repo
  if currentBranch == taskBranch
    then AgentLog.log ("Resuming branch " <> taskBranch)
    else do
      exists <- Git.branchExists repo taskBranch
      if exists
        then do
          AgentLog.log ("Switching to existing branch " <> taskBranch)
          Git.checkout repo taskBranch
        else do
          -- Determine base branch from dependencies
          baseBranch <- findBaseBranch repo task
          if baseBranch /= "live"
            then do
              AgentLog.log ("Basing " <> taskBranch <> " on " <> baseBranch)
              Git.checkout repo baseBranch
            else AgentLog.log ("Basing " <> taskBranch <> " on live")

          Git.createBranch repo taskBranch

  -- Run Amp
  AgentLog.updateActivity "Running Amp agent..."
  exitCode <- runAmp repo task

  case exitCode of
    Exit.ExitSuccess -> do
      AgentLog.log "Agent finished successfully"

      -- Update status to Review (bundled with feature commit)
      TaskCore.updateTaskStatus tid TaskCore.Review []

      -- Commit changes
      -- We should check if there are changes, but 'git add .' is safe.
      Git.commit repo ("feat: implement " <> tid)

      -- Submit for review
      AgentLog.updateActivity "Submitting for review..."

      -- Switch back to worker base
      let base = Core.workerName worker
      Git.checkout repo base

      -- Sync again
      Git.syncWithLive repo

      -- Update status to Review (for signaling)
      TaskCore.updateTaskStatus tid TaskCore.Review []
      Git.commit repo ("task: review " <> tid)

      AgentLog.log ("[✓] Task " <> tid <> " completed")
      AgentLog.update (\s -> s {AgentLog.statusTask = Nothing})
    Exit.ExitFailure code -> do
      AgentLog.log ("Agent failed with code " <> tshow code)
      AgentLog.updateActivity "Agent failed, retrying..."
      threadDelay (10 * 1000000) -- Sleep 10s

runAmp :: FilePath -> TaskCore.Task -> IO Exit.ExitCode
runAmp repo task = do
  let prompt =
        "You are a Worker Agent.\n"
          <> "Your goal is to implement the following task:\n\n"
          <> formatTask task
          <> "\n\nINSTRUCTIONS:\n"
          <> "1. Analyze the codebase (use finder/Grep) to understand where to make changes.\n"
          <> "2. Implement the changes by editing files.\n"
          <> "3. Run tests to verify your work (e.g., 'bild --test Omni/Namespace').\n"
          <> "4. Fix any errors found during testing.\n"
          <> "5. Do NOT update the task status or manage git branches (the system handles that).\n"
          <> "6. When finished and tested, exit.\n\n"
          <> "Context:\n"
          <> "- You are working in '"
          <> Text.pack repo
          <> "'.\n"
          <> "- The task is in namespace '"
          <> fromMaybe "root" (TaskCore.taskNamespace task)
          <> "'.\n"

  let logFile = repo </> "_/llm/amp.log"

  -- Remove old log file
  exists <- Directory.doesFileExist logFile
  when exists (Directory.removeFile logFile)

  Directory.createDirectoryIfMissing True (repo </> "_/llm")

  -- Assume amp is in PATH
  let args = ["--log-level", "debug", "--log-file", "_/llm/amp.log", "--dangerously-allow-all", "-x", Text.unpack prompt]

  let cp = (Process.proc "amp" args) {Process.cwd = Just repo}
  (_, _, _, ph) <- Process.createProcess cp

  tid <- forkIO <| monitorLog logFile ph

  exitCode <- Process.waitForProcess ph
  killThread tid
  pure exitCode

formatTask :: TaskCore.Task -> Text
formatTask t =
  "Task: "
    <> TaskCore.taskId t
    <> "\n"
    <> "Title:      "
    <> TaskCore.taskTitle t
    <> "\n"
    <> "Type:       "
    <> Text.pack (show (TaskCore.taskType t))
    <> "\n"
    <> "Status:     "
    <> Text.pack (show (TaskCore.taskStatus t))
    <> "\n"
    <> "Priority:   "
    <> Text.pack (show (TaskCore.taskPriority t))
    <> "\n"
    <> maybe "" (\p -> "Parent:     " <> p <> "\n") (TaskCore.taskParent t)
    <> maybe "" (\ns -> "Namespace:  " <> ns <> "\n") (TaskCore.taskNamespace t)
    <> "Created:    "
    <> Text.pack (show (TaskCore.taskCreatedAt t))
    <> "\n"
    <> "Updated:    "
    <> Text.pack (show (TaskCore.taskUpdatedAt t))
    <> "\n"
    <> maybe "" (\d -> "Description:\n" <> d <> "\n\n") (TaskCore.taskDescription t)
    <> (if null (TaskCore.taskDependencies t) then "" else "\nDependencies:\n" <> Text.unlines (map formatDep (TaskCore.taskDependencies t)))
  where
    formatDep dep = "  - " <> TaskCore.depId dep <> " [" <> Text.pack (show (TaskCore.depType dep)) <> "]"

monitorLog :: FilePath -> Process.ProcessHandle -> IO ()
monitorLog path ph = do
  waitForFile path
  IO.withFile path IO.ReadMode <| \h -> do
    IO.hSetBuffering h IO.LineBuffering
    go h
  where
    go h = do
      eof <- IO.hIsEOF h
      if eof
        then do
          mExit <- Process.getProcessExitCode ph
          case mExit of
            Nothing -> do
              threadDelay 100000 -- 0.1s
              go h
            Just _ -> pure ()
        else do
          line <- TIO.hGetLine h
          AgentLog.processLogLine line
          go h

waitForFile :: FilePath -> IO ()
waitForFile path = do
  exists <- Directory.doesFileExist path
  if exists
    then pure ()
    else do
      threadDelay 100000
      waitForFile path

findBaseBranch :: FilePath -> TaskCore.Task -> IO Text
findBaseBranch repo task = do
  let deps = TaskCore.taskDependencies task
  -- Filter for blocking dependencies
  let blockingDeps = filter (\d -> TaskCore.depType d == TaskCore.Blocks || TaskCore.depType d == TaskCore.ParentChild) deps

  -- Check if any have unmerged branches
  candidates <-
    flip filterM blockingDeps <| \dep -> do
      let branch = "task/" <> TaskCore.depId dep
      exists <- Git.branchExists repo branch
      if exists
        then do
          merged <- Git.isMerged repo branch "live"
          pure (not merged)
        else pure False

  case candidates of
    (candidate : _) -> pure ("task/" <> TaskCore.depId candidate)
    [] -> pure "live"