package logging

import (
    "bufio"
    "fmt"
    "os"
    "path/filepath"
    "sort"
    "time"
)

type LogEntry struct {
    Path    string
    ModTime time.Time
    Size    int64
}

func LogDir() string {
    home, err := os.UserHomeDir()
    if err != nil {
        return ""
    }
    return filepath.Join(home, ".config", "ai-agent", "logs")
}

func ListLogs(n int) ([]LogEntry, error) {
    return listLogsIn(LogDir(), n)
}

func listLogsIn(dir string, n int) ([]LogEntry, error) {
    entries, err := os.ReadDir(dir)
    if err != nil {
        return nil, fmt.Errorf("read log dir: %w", err)
    }
    var logs []LogEntry
    for _, e := range entries {
        if e.IsDir() {
            continue
        }
        info, err := e.Info()
        if err != nil {
            continue
        }
        logs = append(logs, LogEntry{
            Path:    filepath.Join(dir, e.Name()),
            ModTime: info.ModTime(),
            Size:    info.Size(),
        })
    }
    sort.Slice(logs, func(i, j int) bool {
        return logs[i].ModTime.After(logs[j].ModTime)
    })
    if n > 0 && n < len(logs) {
        logs = logs[:n]
    }
    return logs, nil
}

func LatestLogPath() (string, error) {
    return latestLogPathIn(LogDir())
}

func latestLogPathIn(dir string) (string, error) {
    logs, err := listLogsIn(dir, 1)
    if err != nil {
        return "", err
    }
    if len(logs) == 0 {
        return "", fmt.Errorf("no log files found in %s", dir)
    }
    return logs[0].Path, nil
}

func TailLog(path string, n int) ([]string, error) {
    f, err := os.Open(path)
    if err != nil {
        return nil, fmt.Errorf("open log: %w", err)
    }
    defer f.Close()
    var lines []string
    scanner := bufio.NewScanner(f)
    for scanner.Scan() {
        lines = append(lines, scanner.Text())
    }
    if err := scanner.Err(); err != nil {
        return nil, fmt.Errorf("read log: %w", err)
    }
    if n > 0 && n < len(lines) {
        lines = lines[len(lines)-n:]
    }
    return lines, nil
}