package builder

import (
  "os/exec"
  "io"
  "os"
  "time"
  "io/fs"
  "path/filepath"
  "errors"
  "github.com/fsnotify/fsnotify"
  "bufio"
  "regexp"
  "strconv"
  "lcthw.dev/go/ttarpit/config"
  "lcthw.dev/go/ttarpit/data"
  . "lcthw.dev/go/ttarpit/debug"
)

type ErrorHandler func (data.ErrInfo) 

const (
  START=0
  RUNNING=1
  FAILED=2
  PASSED=3
)

type Builder struct {
  settings config.Config 
  OnError ErrorHandler

  BuildState int
  HadErrors bool
}

func New(settings config.Config, handler ErrorHandler) (*Builder) {
  builder := new(Builder)

  builder.settings = settings
  builder.OnError = handler

  return builder
}

func (build *Builder) ParseErrInfo(line string, reg *regexp.Regexp) (data.ErrInfo, bool) {
  var info data.ErrInfo

  matches := reg.FindStringSubmatch(line)
  if matches == nil {
    return info, false
  }

  et_index := reg.SubexpIndex("ErrType")
  if et_index != -1 {
    info.ErrType = matches[et_index]
  }

  // BUG: use reflect
  info.File = matches[reg.SubexpIndex("File")]

  info.Line, _ = strconv.Atoi(matches[reg.SubexpIndex("Line")])

  info.Col, _ = strconv.Atoi(matches[reg.SubexpIndex("Col")])

  info.Message = matches[reg.SubexpIndex("Message")]

  return info, true
}


func (build *Builder) LaunchLogger(in io.Reader, out io.Writer, err error) {
  if err != nil { Log.Fatal(err) }

  go func() {
    scan := bufio.NewScanner(in)

    for scan.Scan() {
      for _, reg := range build.settings.TriggerRegex {
        line := scan.Text()

        errinfo, ok := build.ParseErrInfo(line, reg)

        if ok {
          build.OnError(errinfo)
          build.HadErrors = true
        }
      }
    }
  }()
}


func (build *Builder) LaunchProcess(proc *config.Process) {
  proc.ExecCmd = exec.Command(proc.Command, proc.Args...)
  if errors.Is(proc.ExecCmd.Err, exec.ErrDot) {
    proc.ExecCmd.Err = nil
  }

  Log.Println("STARTING", proc.Command)

  stderr, err := proc.ExecCmd.StderrPipe();
  build.LaunchLogger(stderr, os.Stdout, err)

  stdout, err := proc.ExecCmd.StdoutPipe();
  build.LaunchLogger(stdout, os.Stdout, err)

  err = proc.ExecCmd.Start()
  if err != nil {
    Log.Fatalf("FAIL %s %s err=%v", proc.Command, proc.Args, err)
  }

  Log.Println("WAITING for", proc.Command)

  proc.ExecCmd.Wait()
  Log.Println("PROCESS", proc.Command, "EXITED")
}

func (build *Builder) MatchesPath(fp string) bool {
  fp = filepath.ToSlash(fp)

  for _, reg := range build.settings.IncludeRegex {
    matches := reg.MatchString(fp)

    if matches {
      return true
    }
  }

  return false
}

func (build *Builder) BeginBuild() bool {
  if build.BuildState != RUNNING {
    build.BuildState = RUNNING
    build.HadErrors = false
    return true
  } else {
    return false
  }
}

func (build *Builder) EndBuild() {
  if build.HadErrors {
    build.BuildState = FAILED
  } else {
    build.BuildState = PASSED
  }
}

func (build *Builder) RunBuild() {
  if build.BeginBuild() {
    defer build.EndBuild() 

    Log.Println("CONFIG:", build.settings.ConfigPath)
    Log.Println("COMMANDs:", build.settings.Processes)

    for name, proc := range build.settings.Processes {
      Log.Println("PROCESS:", name)

      build.LaunchProcess(&proc)
    }

    time.Sleep(1000 * time.Millisecond)
  } else {
    Log.Println("!!!! BUILD SKIP, already running")
  }
}

func (build *Builder) AddWatchDir(watcher *fsnotify.Watcher, name string) error {
  return filepath.WalkDir(name,
  func(path string, d fs.DirEntry, err error) error {
    if err != nil {
      Log.Printf("WATCH ERROR! walking=%s path=%s: err=%v", name, path, err)
      return err
    }

    if d.IsDir() {
      Log.Println("WATCHING: ", path)
      err = watcher.Add(path)
      if err != nil {
        Log.Printf("failed to watch %s", path)
        return err
      }
    }

    return nil
  })
}

func (build *Builder) WatchDir() {
  watcher, err := fsnotify.NewWatcher()
  if err != nil {
    Log.Fatal("Failed to start fsnotify", err)
  }
  defer watcher.Close()

  go func() {
    for {
      select {
      case event, ok := <-watcher.Events:
        if !ok {
          return
        }

        if event.Has(fsnotify.Create) {
          Log.Println("---> CREATE", event.Name)
          build.AddWatchDir(watcher, event.Name)
        } else if event.Has(fsnotify.Write) {
          // check if match then do thing
          if build.MatchesPath(event.Name) {
            go build.RunBuild()
          }
        } else {
          Log.Println("event:", event)
        }
      case err, ok := <-watcher.Errors:
        if !ok {
          return
        }
        Log.Println("error: ", err)
      }
    }
  }()

  err = build.AddWatchDir(watcher, ".")

  if err != nil {
    Log.Fatal(err, "Failed to watch .")
  }

  <-make(chan struct{})
}