package cmdn

import (
	"bufio"
	"context"
	"errors"
	"fmt"
	"git.noahlan.cn/noahlan/ntool/ndef"
	"git.noahlan.cn/noahlan/ntool/nstr"
	atomic2 "git.noahlan.cn/noahlan/ntool/nsys/atomic"
	"io"
	"log"
	"os/exec"
	"strings"
	"sync"
	"sync/atomic"
	"time"
)

const (
	DefaultBlockPrefix    = "block"
	DefaultNonBlockPrefix = "non-block"
	DefaultTimeout        = time.Second * 0
)

var (
	ErrBrokenPipe = errors.New("broken low-level pipe")

	defaultStartupDecidedFunc = func(_ *strings.Builder, line string) bool {
		return true
	}
	defaultEndLineDecidedFunc = func(sb *strings.Builder, line string) bool {
		return true
	}

	defaultReadIDFunc = func(serializer ndef.Serializer, data string) (string, error) {
		return "", nil
	}
)

type (
	pendingMsg struct {
		id       string
		chWait   chan struct{}
		callback CallbackFunc
	}
)

type (
	LineFunc     func(sb *strings.Builder, line string) bool
	ReadIDFunc   func(serializer ndef.Serializer, data string) (string, error)
	CallbackFunc func(serializer ndef.Serializer, data string)

	Options struct {
		Marshaler          ndef.Marshaler   // 序列化
		Unmarshaler        ndef.Unmarshaler // 反序列化
		StartupDecidedFunc LineFunc         // 启动决议方法
		EndLineDecidedFunc LineFunc         // 行尾判断方法
		ReadIDFunc         ReadIDFunc       // 从数据中获取ID的方法
		Timeout            time.Duration    // 超时时间
	}
	Option func(opt *Options)
)

// Processor 处理器
type Processor struct {
	*Options
	Context    context.Context
	cancelFunc context.CancelFunc

	Cmd    *exec.Cmd      // CMD
	stdIn  io.WriteCloser // 标准输入通道
	stdOut io.ReadCloser  // 标准输出通道
	stdErr io.ReadCloser  // 标准错误输出通道，一些程序会在此通道输出错误信息和一般信息

	isBlock   bool          // 底层是否为同步逻辑
	isStartup *atomic.Bool  // 子进程是否真正启动完毕
	chStart   chan struct{} // 程序真正启动完毕信号

	chSend  chan ICommand // 待发送数据
	chWrite chan []byte   // 实际发送的数据

	sendIdx       *atomic2.AtomicInt64   // 发送缓冲ID
	recIdx        *atomic2.AtomicInt64   // 接收缓冲ID
	pendingMsgMap map[string]*pendingMsg // 发送缓存区map

	*sync.Mutex
}

func NewProcessor(block bool, opts ...Option) *Processor {
	defaultSerializer := NewPlainSerializer()
	tmp := &Processor{
		Options: &Options{
			Marshaler:          defaultSerializer,
			Unmarshaler:        defaultSerializer,
			StartupDecidedFunc: defaultStartupDecidedFunc,
			EndLineDecidedFunc: defaultEndLineDecidedFunc,
			ReadIDFunc:         defaultReadIDFunc,
			Timeout:            DefaultTimeout,
		},

		isBlock:   block,
		isStartup: &atomic.Bool{},
		chStart:   make(chan struct{}),

		chSend:        make(chan ICommand, 64),
		chWrite:       make(chan []byte, 64*8),
		sendIdx:       atomic2.NewAtomicInt64(),
		recIdx:        atomic2.NewAtomicInt64(),
		pendingMsgMap: make(map[string]*pendingMsg),
		Mutex:         &sync.Mutex{},
	}

	for _, opt := range opts {
		opt(tmp.Options)
	}

	if tmp.Timeout == 0 {
		tmp.Context, tmp.cancelFunc = context.WithCancel(context.Background())
	} else {
		tmp.Context, tmp.cancelFunc = context.WithTimeout(context.Background(), tmp.Timeout)
	}
	return tmp
}

func (s *Processor) Run(name string, args ...string) error {
	s.Cmd = exec.CommandContext(s.Context, name, args...)
	s.stdIn, _ = s.Cmd.StdinPipe()
	s.stdOut, _ = s.Cmd.StdoutPipe()
	s.stdErr, _ = s.Cmd.StderrPipe()

	setProcessGroupID(s.Cmd)

	err := s.Cmd.Start()

	go func() {
		err := s.Cmd.Wait()
		if err != nil {
			log.Println(fmt.Sprintf("错误：命令行 %+v", err))
		}
		_ = s.stdErr.Close()
		_ = s.stdIn.Close()
		_ = s.stdOut.Close()
	}()
	s.listen()

	return err
}

// Listen 开始监听
func (s *Processor) listen() {
	go s.handle(s.stdOut, "stdOut")
	go s.handle(s.stdErr, "stdErr")

	// 等待程序启动完毕
	select {
	case <-s.chStart:
	}

	go s.writeLoop()
}

func (s *Processor) Stop() error {
	s.Lock()
	defer s.Unlock()

	s.cancelFunc()
	return terminateProcess(s.Cmd.Process.Pid)
}

// Exec 异步执行命令
func (s *Processor) Exec(data ICommand, callback CallbackFunc) (err error) {
	_, err = s.exec(data, false, callback)
	return
}

// ExecAsync 同步执行命令
func (s *Processor) ExecAsync(data ICommand, callback CallbackFunc) error {
	pm, err := s.exec(data, true, callback)
	if err != nil {
		return err
	}

	// 同步等待消息回复
	<-pm.chWait

	return err
}

func (s *Processor) exec(data ICommand, withWait bool, callback CallbackFunc) (pm *pendingMsg, err error) {
	defer func() {
		if e := recover(); e != nil {
			err = ErrBrokenPipe
			_ = s.sendIdx.DecrementAndGet()
		}
	}()

	cID := data.MessageID()
	if len(cID) == 0 {
		if s.isBlock {
			// block-1
			cID = fmt.Sprintf("%s-%d", DefaultBlockPrefix, s.sendIdx.IncrementAndGet())
		} else {
			cID = fmt.Sprintf("%s-%s-%d", DefaultNonBlockPrefix, cID, s.sendIdx.IncrementAndGet())
			// error
			return nil, errors.New("异步底层必须消息必须传递消息ID")
		}
	}

	var chWait chan struct{}
	if withWait {
		chWait = make(chan struct{})
	}
	pm = &pendingMsg{
		id:       cID,
		chWait:   chWait,
		callback: callback,
	}

	s.Lock()
	s.pendingMsgMap[pm.id] = pm
	s.Unlock()

	s.chSend <- data
	return pm, err
}

func (s *Processor) writeLoop() {
	defer func() {
		close(s.chSend)
		close(s.chWrite)
	}()

	for {
		select {
		case <-s.Context.Done():
			return
		case data := <-s.chSend:
			var (
				bytes []byte
				err   error
			)
			bytes, err = s.Marshaler.Marshal(data)
			if err != nil {
				fmt.Println(fmt.Sprintf("序列化失败: %+v", err))
				break
			}
			s.chWrite <- bytes
		case data := <-s.chWrite:
			// 实际写入数据
			fmt.Println(fmt.Sprintf("发送数据: [%s]", string(data)))

			data = append(data, '\n')
			if _, err := s.stdIn.Write(data); err != nil {
				return
			}
		}
	}
}

func (s *Processor) handle(reader io.ReadCloser, typ string) {
	defer func() {
		_ = reader.Close()
	}()

	buffer := bufio.NewReader(reader)
	endLine := false
	content := strings.Builder{}
	for {
		select {
		case <-s.Context.Done():
			return
		default:
			break
		}
		lineBytes, isPrefix, err := buffer.ReadLine()
		if err != nil || err == io.EOF {
			fmt.Println(fmt.Sprintf("[%s] 读取数据时发生错误: %v", typ, err))
			break
		}

		line, err := s.readBytesString(lineBytes)
		if err != nil {
			break
		}

		if !s.Started() {
			fmt.Println(fmt.Sprintf("[%s] 接收普通消息:[%s]", typ, line))

			// 判断程序成功启动 外部逻辑
			if s.StartupDecidedFunc(&content, line) {
				s.storeStarted(true)
				s.chStart <- struct{}{}
				fmt.Println(fmt.Sprintf("[%s] 启动完毕，等待输出...", typ))
			}
			continue
		}

		content.WriteString(line)
		if !isPrefix && len(line) > 0 {
			content.WriteByte('\n')
		}
		// 最后一行的判定逻辑
		if !endLine && s.EndLineDecidedFunc(&content, line) {
			endLine = true
		}

		if endLine {
			endLine = false
			cStr := content.String()
			if len(cStr) > 0 {
				cStr = cStr[:len(cStr)-1]
			}
			content.Reset()

			revID, err := s.ReadIDFunc(ndef.NewSerializerWrapper(s.Marshaler, s.Unmarshaler), cStr)
			if err != nil {
				continue
			}
			//fmt.Println(fmt.Sprintf("[%s] 接收指令消息:[%s]", typ, cStr))

			// block 需要自行维护ID，是无法透传的
			if len(revID) <= 0 {
				revID = fmt.Sprintf("%s-%d", DefaultBlockPrefix, s.recIdx.IncrementAndGet())
			}

			pending, ok := s.pendingMsgMap[revID]
			if !ok {
				fmt.Println("找不到已发送数据，无法对应处理数据！")
				continue
			}
			delete(s.pendingMsgMap, revID)

			go func() {
				pending.callback(ndef.NewSerializerWrapper(s.Marshaler, s.Unmarshaler), cStr)
				if pending.chWait != nil {
					pending.chWait <- struct{}{}
				}
			}()
		}
	}
}

func (s *Processor) readBytesString(data []byte) (string, error) {
	// 编码
	if nstr.Charset(data) == nstr.GBK {
		gbk, err := nstr.ToGBK(data)
		if err != nil {
			return "", err
		}
		return string(gbk), nil
	} else {
		return string(data), nil
	}
}

// Started 是否启动完成
func (s *Processor) Started() bool {
	return s.isStartup.Load()
}

func (s *Processor) storeStarted(val bool) {
	s.isStartup.Store(val)
}