package git

import (
	"context"
	"strconv"
	"strings"
	"time"
)

// Commit 表示一条 git log 记录。
type Commit struct {
	Hash    string
	Author  string
	Email   string
	Date    time.Time
	Subject string
}

// Log 返回 dir 的最近 n 条提交历史。n <= 0 时默认 50 条。
func (r *DefaultRunner) Log(ctx context.Context, dir string, n int) ([]Commit, error) {
	ctx, cancel := withCtx(ctx, r.cfg.OpsTimeout)
	defer cancel()
	if n <= 0 {
		n = 50
	}
	out, _, err := r.exec(ctx, dir, nil, "log", "--format=%H%x00%an%x00%ae%x00%aI%x00%s%x00", "-n", strconv.Itoa(n))
	if err != nil {
		return nil, err
	}
	return parseLog(out), nil
}

func parseLog(buf []byte) []Commit {
	if len(buf) == 0 {
		return nil
	}
	parts := strings.Split(string(buf), "\x00")
	var commits []Commit
	// parts 以空字符串结尾（因为 format 最后有 %x00），所以每 5 个字段为一组。
	for i := 0; i+4 < len(parts); i += 5 {
		hash := parts[i]
		if hash == "" {
			continue
		}
		author := parts[i+1]
		email := parts[i+2]
		dateStr := parts[i+3]
		subject := parts[i+4]

		date, _ := time.Parse(time.RFC3339, dateStr)

		commits = append(commits, Commit{
			Hash:    hash,
			Author:  author,
			Email:   email,
			Date:    date,
			Subject: subject,
		})
	}
	return commits
}