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package common

import (
	"bufio"
	"fmt"
	"os"
)

type LogType int

const (
	LOG_CREATED = LogType(iota)
	LOG_APPROVED
	LOG_DELETED
)

type LogEntry struct {
	Hash string
	Type LogType
}

type Log []LogEntry

// senary keeps issues and change requests on-disk and maintains a log of actions over these artifacts i.e. created, approved or deleted.
// logs can in theory be "collapsed" by permanently deleting create and approved entries if a deleted entry also exists
// we don't do this here, but may want to build a standalone command to do this in the future.
func WriteToLog(filename string, hash string, t LogType) error {
	file, err := os.OpenFile(filename, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0644)
	if err != nil {
		return err
	}
	defer file.Close()
	_, err = file.WriteString(fmt.Sprintf("%s %d\n", hash, t))
	return err
}

// iterate over each log entry and callback to the provided function
func LogIer(filename string, callback func(LogEntry)) error {
	file, err := os.Open(filename)
	if err != nil {
		return err
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		logline := scanner.Text()
		logEntry := LogEntry{}
		n, err := fmt.Sscanf(logline, "%s %d", &logEntry.Hash, &logEntry.Type)

		// corrupted or malformed log entry, we can't recover from this so abort...
		if n != 2 || err != nil {
			return err
		}
		callback(logEntry)
	}

	return scanner.Err()
}