package main

import (
	"bufio"
	"fmt"
	"os"
	"regexp"
	"strconv"
)

//  (2022-07-08 16:54:15.587099)  can0  100   [8]  00 00 00 00 00 00 64 00
const expr = "\\((.*)\\)\\s+can\\d+\\s+(\\d+)\\s+\\[\\d\\]\\s+([A-F0-9]+)\\s+([A-F0-9]+)\\s+([A-F0-9]+)\\s+([A-F0-9]+)\\s+([A-F0-9]+)\\s+([A-F0-9]+)\\s+([A-F0-9]+)\\s+([A-F0-9]+)"
const length = 11

var pattern = regexp.MustCompile(expr)

func Readfile(filename *string) <-chan *CanFrame {
	c := make(chan *CanFrame)

	go func() {
		defer close(c)

		file, err := os.Open(*filename)
		if err != nil {
			fmt.Println(err)
			return
		}
		defer file.Close()

		scanner := bufio.NewScanner(file)
		for scanner.Scan() {
			text := scanner.Text()
			c <- fromString(&text)
		}

		if err := scanner.Err(); err != nil {
			fmt.Println(err)
		}
	}()

	return c
}

func fromString(text *string) *CanFrame {
	submatch := pattern.FindStringSubmatch(*text)
	if len(submatch) == length {
		canid, err := strconv.ParseUint(submatch[2], 16, 0)
		if err != nil {
			return nil
		}

		payload := make([]uint8, 8)
		for idx, octet := range submatch[3:] {
			val, err := strconv.ParseUint(octet, 16, 0)
			if err != nil {
				fmt.Println(err)
				continue
			}

			payload[idx] = uint8(val)
		}

		return &CanFrame{
			date:    submatch[1],
			canid:   uint32(canid),
			payload: payload,
		}
	}

	return nil
}