package serialport

import (
	"fmt"
	"io"
	"log"
	"time"

	"go.bug.st/serial"

	"bjhardman.cn/bjhardman/hougai_insize_micrometer/insize"
)

type Port struct {
	port   serial.Port
	frames chan insize.Frame
	errs   chan error
	done   chan struct{}
}

func Open(name string, baud int) (*Port, error) {
	mode := &serial.Mode{
		BaudRate: baud,
		DataBits: 8,
		Parity:   serial.NoParity,
		StopBits: serial.OneStopBit,
	}
	sp, err := serial.Open(name, mode)
	if err != nil {
		return nil, fmt.Errorf("打开串口 %s: %w", name, err)
	}
	if err := sp.SetReadTimeout(500 * time.Millisecond); err != nil {
	}

	p := &Port{
		port:   sp,
		frames: make(chan insize.Frame, 16),
		errs:   make(chan error, 4),
		done:   make(chan struct{}),
	}
	go p.readLoop()
	return p, nil
}

func (p *Port) Frames() <-chan insize.Frame { return p.frames }

func (p *Port) Errors() <-chan error { return p.errs }

func (p *Port) Close() error {
	close(p.done)
	return p.port.Close()
}

func (p *Port) readLoop() {
	reader := insize.NewReader(p.port)
	for {
		select {
		case <-p.done:
			return
		default:
		}
		f, err := reader.ReadFrame()
		if err != nil {
			if err == io.EOF || err == io.ErrUnexpectedEOF {
				p.errs <- fmt.Errorf("串口读取结束: %w", err)
				return
			}
			log.Printf("serialport: 跳过非法帧: %v", err)
			continue
		}
		select {
		case p.frames <- f:
		case <-p.done:
			return
		}
	}
}