package logger

import (
	"database/sql"
	"fmt"
	"os"
	"path/filepath"
	"time"

	_ "github.com/mattn/go-sqlite3"
)

const (
	LevelDebug = "debug"
	LevelInfo  = "info"
	LevelError = "error"
)

type Logger struct {
	db            *sql.DB
	dbPath        string
	retentionDays int
}

// New opens (or creates) logs.db inside logDir, applies the schema, and runs
// an initial retention purge. retentionDays <= 0 falls back to 7.
func New(logDir string, retentionDays int) (*Logger, error) {
	if retentionDays <= 0 {
		retentionDays = 7
	}
	if err := os.MkdirAll(logDir, 0755); err != nil {
		return nil, fmt.Errorf("creating log directory: %w", err)
	}

	dbPath := filepath.Join(logDir, "logs.db")
	db, err := sql.Open("sqlite3", dbPath+"?_journal_mode=WAL&_busy_timeout=5000")
	if err != nil {
		return nil, fmt.Errorf("opening log db: %w", err)
	}

	schema := `
	CREATE TABLE IF NOT EXISTS logs (
		id      INTEGER PRIMARY KEY AUTOINCREMENT,
		ts      TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
		level   TEXT NOT NULL,
		message TEXT NOT NULL,
		file    TEXT,
		extra   TEXT
	);
	CREATE INDEX IF NOT EXISTS idx_logs_ts_level ON logs(ts, level);
	`
	if _, err := db.Exec(schema); err != nil {
		db.Close()
		return nil, fmt.Errorf("applying log schema: %w", err)
	}

	l := &Logger{db: db, dbPath: dbPath, retentionDays: retentionDays}
	l.purge()
	return l, nil
}

func (l *Logger) purge() {
	cutoff := fmt.Sprintf("-%d days", l.retentionDays)
	_, _ = l.db.Exec(`DELETE FROM logs WHERE ts < datetime('now', ?)`, cutoff)
}

func (l *Logger) write(level, message, file, extra string) {
	_, _ = l.db.Exec(
		`INSERT INTO logs(level, message, file, extra) VALUES(?, ?, ?, ?)`,
		level, message, nullIfEmpty(file), nullIfEmpty(extra),
	)
}

func nullIfEmpty(s string) interface{} {
	if s == "" {
		return nil
	}
	return s
}

func stamp() string {
	return time.Now().Format("2006-01-02 15:04:05")
}

func (l *Logger) Info(message string) {
	fmt.Fprintf(os.Stdout, "[%s] INFO: %s\n", stamp(), message)
	l.write(LevelInfo, message, "", "")
}

// Progress prints to stdout only, without a db row. For high-frequency,
// ephemeral telemetry (live encode progress) that would otherwise bury real
// events in logs.db and churn until retention purges it.
func (l *Logger) Progress(message string) {
	fmt.Fprintf(os.Stdout, "[%s] INFO: %s\n", stamp(), message)
}

func (l *Logger) Error(message, errStr string) {
	msg := fmt.Sprintf("%s: %s", message, errStr)
	fmt.Fprintf(os.Stderr, "[%s] ERROR: %s\n", stamp(), msg)
	l.write(LevelError, msg, "", "")
}

func (l *Logger) ErrorFile(file, message, errStr string) {
	msg := fmt.Sprintf("%s: %s", message, errStr)
	fmt.Fprintf(os.Stderr, "[%s] ERROR: %s (file: %s)\n", stamp(), msg, file)
	l.write(LevelError, msg, file, "")
}

// Debug records a debug entry to the database only. extra is an opaque string,
// typically JSON, used for ffprobe output, API response bodies, or command
// stdout/stderr captures. Pass "" if not applicable.
func (l *Logger) Debug(message, file, extra string) {
	l.write(LevelDebug, message, file, extra)
}

// LogEntry is one row returned by RecentLogs, shaped for the status feed.
type LogEntry struct {
	TS      string `json:"ts"`
	Level   string `json:"level"`
	Message string `json:"message"`
	File    string `json:"file,omitempty"`
}

// RecentLogs returns the newest-first non-debug entries, capped at n. Debug
// rows (per-command ffprobe/ffmpeg/API dumps) are excluded — the status feed
// wants real events, not invocation noise.
func (l *Logger) RecentLogs(n int) ([]LogEntry, error) {
	if l.db == nil {
		return nil, nil
	}
	rows, err := l.db.Query(
		`SELECT ts, level, message, COALESCE(file, '') FROM logs WHERE level != ? ORDER BY id DESC LIMIT ?`,
		LevelDebug, n)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []LogEntry
	for rows.Next() {
		var e LogEntry
		if err := rows.Scan(&e.TS, &e.Level, &e.Message, &e.File); err != nil {
			return nil, err
		}
		out = append(out, e)
	}
	return out, rows.Err()
}

func (l *Logger) Close() {
	if l.db == nil {
		return
	}
	l.purge()
	l.db.Close()
	l.db = nil
}