// Package logging supplies readable console output and rotating structured files.
package logging

import (
	"fmt"
	"os"
	"path/filepath"

	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"gopkg.in/natefinch/lumberjack.v2"
)

type Options struct {
	Directory, Level                  string
	MaxSizeMB, MaxBackups, MaxAgeDays int
}

func New(o Options) (*zap.Logger, func(), error) {
	level, err := zapcore.ParseLevel(o.Level)
	if err != nil {
		return nil, nil, fmt.Errorf("invalid LOG_LEVEL")
	}
	if o.Directory == "" || o.MaxSizeMB < 1 || o.MaxBackups < 1 || o.MaxAgeDays < 1 {
		return nil, nil, fmt.Errorf("invalid logging configuration")
	}
	if err := os.MkdirAll(o.Directory, 0750); err != nil {
		return nil, nil, fmt.Errorf("create log directory: %w", err)
	}
	path := filepath.Join(o.Directory, "veyra.log")
	f, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
	if err != nil {
		return nil, nil, fmt.Errorf("open log file: %w", err)
	}
	if err := f.Close(); err != nil {
		return nil, nil, fmt.Errorf("close initial log file: %w", err)
	}
	file := &lumberjack.Logger{Filename: path, MaxSize: o.MaxSizeMB, MaxBackups: o.MaxBackups, MaxAge: o.MaxAgeDays, Compress: true, LocalTime: true}
	encoder := zap.NewProductionEncoderConfig()
	encoder.TimeKey = "time"
	encoder.MessageKey = "message"
	encoder.EncodeTime = zapcore.ISO8601TimeEncoder
	console := encoder
	console.EncodeLevel = zapcore.CapitalLevelEncoder
	core := zapcore.NewTee(
		zapcore.NewCore(zapcore.NewConsoleEncoder(console), zapcore.Lock(zapcore.AddSync(os.Stdout)), level),
		zapcore.NewCore(zapcore.NewJSONEncoder(encoder), zapcore.AddSync(file), level),
	)
	logger := zap.New(core, zap.AddCaller(), zap.AddStacktrace(zapcore.DPanicLevel))
	return logger, func() { _ = logger.Sync(); _ = file.Close() }, nil
}