package logging

import (
	"fmt"
	"io"
	"os"
	"strings"

	"github.com/sirupsen/logrus"

	"git.wxccs.org/iceking2nd/winauth-go/internal/global"
)

// Options controls logger initialization from CLI flags.
type Options struct {
	// Level is one of: panic, fatal, error, warn, info, debug, trace.
	// Numeric forms (0..6) are also accepted to mirror the legacy convention
	// used in CLAUDE.local.md ("Trace(6)", "Debug(5)").
	Level string

	// File, if non-empty, enables file logging in addition to console output.
	// The file is opened with append + create semantics.
	File string

	// Console forces console output to be visible. On Windows this is the
	// signal used by the cobra entry point to allocate / show a console
	// window for a GUI build. The logger itself always writes to stderr; this
	// field is kept here so that the entry point can read it through the
	// same Options struct.
	Console bool
}

// Init configures the global.Log logger according to opts.
// Returns the opened file handle (or nil) so the caller can close it on exit.
func Init(opts Options) (io.Closer, error) {
	const fn = "internal.logging.Init"

	lvl, err := parseLevel(opts.Level)
	if err != nil {
		return nil, err
	}

	global.Log.SetLevel(lvl)
	global.Log.SetFormatter(&logrus.TextFormatter{
		FullTimestamp:   true,
		TimestampFormat: "2006-01-02 15:04:05.000",
		DisableQuote:    false,
	})

	var closer io.Closer
	if strings.TrimSpace(opts.File) != "" {
		f, ferr := os.OpenFile(opts.File, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
		if ferr != nil {
			return nil, fmt.Errorf("open log file %q: %w", opts.File, ferr)
		}
		global.Log.SetOutput(io.MultiWriter(os.Stderr, f))
		closer = f
	} else {
		global.Log.SetOutput(os.Stderr)
	}

	global.Log.WithField("func", fn).
		WithField("level", lvl.String()).
		WithField("file", opts.File).
		Debug("logger initialized")

	return closer, nil
}

// parseLevel accepts either the textual logrus level names or the numeric
// 0..6 form used in CLAUDE.local.md.
func parseLevel(s string) (logrus.Level, error) {
	s = strings.TrimSpace(strings.ToLower(s))
	if s == "" {
		return logrus.InfoLevel, nil
	}
	switch s {
	case "0", "panic":
		return logrus.PanicLevel, nil
	case "1", "fatal":
		return logrus.FatalLevel, nil
	case "2", "error":
		return logrus.ErrorLevel, nil
	case "3", "warn", "warning":
		return logrus.WarnLevel, nil
	case "4", "info":
		return logrus.InfoLevel, nil
	case "5", "debug":
		return logrus.DebugLevel, nil
	case "6", "trace":
		return logrus.TraceLevel, nil
	}
	return logrus.InfoLevel, fmt.Errorf("unknown log level %q", s)
}