package config

import (
	"bufio"
	"os"
	"path/filepath"
	"strings"
)

const defaultAddr = ":8080"
const defaultDataDir = ".platform-data"
const defaultStorageBackend = "file"

type Config struct {
	Addr           string
	StorageBackend string
	MySQLDSN       string
	DataDir        string
	MetadataPath   string
	LogDir         string
	LogBodyBackend string
}

func Load() Config {
	loadLocalEnvFiles()

	addr := os.Getenv("PLATFORM_ADDR")
	if addr == "" {
		addr = defaultAddr
	}
	dataDir := strings.TrimSpace(os.Getenv("PLATFORM_DATA_DIR"))
	if dataDir == "" {
		dataDir = defaultDataDir
	}
	metadataPath := strings.TrimSpace(os.Getenv("PLATFORM_METADATA_PATH"))
	if metadataPath == "" {
		metadataPath = filepath.Join(dataDir, "metadata.json")
	}
	logDir := strings.TrimSpace(os.Getenv("PLATFORM_LOG_DIR"))
	if logDir == "" {
		logDir = filepath.Join(dataDir, "logs")
	}
	storageBackend := strings.TrimSpace(os.Getenv("PLATFORM_STORAGE_BACKEND"))
	if storageBackend == "" {
		storageBackend = defaultStorageBackend
	}
	logBodyBackend := strings.TrimSpace(os.Getenv("PLATFORM_LOG_BODY_BACKEND"))

	return Config{
		Addr:           addr,
		StorageBackend: storageBackend,
		MySQLDSN:       strings.TrimSpace(os.Getenv("PLATFORM_MYSQL_DSN")),
		DataDir:        dataDir,
		MetadataPath:   metadataPath,
		LogDir:         logDir,
		LogBodyBackend: logBodyBackend,
	}
}

func loadLocalEnvFiles() {
	candidates := []string{".env", filepath.Join("platform", ".env")}
	for _, path := range candidates {
		loadEnvFile(path)
	}
}

func loadEnvFile(path string) {
	file, err := os.Open(path)
	if err != nil {
		return
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		key, value, ok := parseEnvLine(scanner.Text())
		if !ok {
			continue
		}
		if _, exists := os.LookupEnv(key); exists {
			continue
		}
		_ = os.Setenv(key, value)
	}
}

func parseEnvLine(line string) (string, string, bool) {
	line = strings.TrimSpace(line)
	if line == "" || strings.HasPrefix(line, "#") {
		return "", "", false
	}
	line = strings.TrimSpace(strings.TrimPrefix(line, "export "))
	key, value, found := strings.Cut(line, "=")
	if !found {
		return "", "", false
	}
	key = strings.TrimSpace(key)
	if key == "" || strings.ContainsAny(key, " \t") {
		return "", "", false
	}
	value = strings.TrimSpace(stripInlineComment(strings.TrimSpace(value)))
	if len(value) >= 2 {
		if (value[0] == '"' && value[len(value)-1] == '"') || (value[0] == '\'' && value[len(value)-1] == '\'') {
			value = value[1 : len(value)-1]
		}
	}
	return key, value, true
}

func stripInlineComment(value string) string {
	inSingleQuote := false
	inDoubleQuote := false
	for index, char := range value {
		switch char {
		case '\'':
			if !inDoubleQuote {
				inSingleQuote = !inSingleQuote
			}
		case '"':
			if !inSingleQuote {
				inDoubleQuote = !inDoubleQuote
			}
		case '#':
			if !inSingleQuote && !inDoubleQuote && index > 0 && value[index-1] == ' ' {
				return strings.TrimSpace(value[:index])
			}
		}
	}
	return value
}