package config

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

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

// defaultBuilderImage names an explicit toolchain version rather than a
// floating tag such as latest. Operators who want digest pinning override
// PLATFORM_BUILDER_IMAGE with an image@sha256:... reference.
const defaultBuilderImage = "browser-platform-distribution-builder:1.0.0"
const defaultBuilderTimeoutSeconds = 1800

type Config struct {
	Addr                   string
	StorageBackend         string
	MySQLDSN               string
	DataDir                string
	MetadataPath           string
	LogDir                 string
	ArtifactDir            string
	LogBodyBackend         string
	BootstrapAdminEmail    string
	BootstrapAdminPassword string
	SecretEnvelopeKey      string
	AIProviderMode         string
	BuilderDockerBinary    string
	BuilderImage           string
	BuilderSourceDir       string
	BuilderWorkspaceDir    string
	BuilderTimeoutSeconds  int
}

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")
	}
	artifactDir := strings.TrimSpace(os.Getenv("PLATFORM_ARTIFACT_DIR"))
	if artifactDir == "" {
		artifactDir = filepath.Join(dataDir, "artifacts")
	}
	storageBackend := strings.TrimSpace(os.Getenv("PLATFORM_STORAGE_BACKEND"))
	if storageBackend == "" {
		storageBackend = defaultStorageBackend
	}
	logBodyBackend := strings.TrimSpace(os.Getenv("PLATFORM_LOG_BODY_BACKEND"))
	builderWorkspaceDir := strings.TrimSpace(os.Getenv("PLATFORM_BUILDER_WORKSPACE_DIR"))
	if builderWorkspaceDir == "" {
		builderWorkspaceDir = filepath.Join(dataDir, "distribution-builds")
	}

	return Config{
		Addr:                   addr,
		StorageBackend:         storageBackend,
		MySQLDSN:               strings.TrimSpace(os.Getenv("PLATFORM_MYSQL_DSN")),
		DataDir:                dataDir,
		MetadataPath:           metadataPath,
		LogDir:                 logDir,
		ArtifactDir:            artifactDir,
		LogBodyBackend:         logBodyBackend,
		BootstrapAdminEmail:    strings.TrimSpace(os.Getenv("PLATFORM_BOOTSTRAP_ADMIN_EMAIL")),
		BootstrapAdminPassword: os.Getenv("PLATFORM_BOOTSTRAP_ADMIN_PASSWORD"),
		SecretEnvelopeKey:      os.Getenv("PLATFORM_SECRET_ENVELOPE_KEY"),
		AIProviderMode:         defaultString(strings.TrimSpace(os.Getenv("PLATFORM_AI_PROVIDER_MODE")), "live"),
		BuilderDockerBinary:    defaultString(strings.TrimSpace(os.Getenv("PLATFORM_BUILDER_DOCKER_BINARY")), defaultBuilderDockerBinary),
		BuilderImage:           defaultString(strings.TrimSpace(os.Getenv("PLATFORM_BUILDER_IMAGE")), defaultBuilderImage),
		BuilderSourceDir:       strings.TrimSpace(os.Getenv("PLATFORM_BUILDER_SOURCE_DIR")),
		BuilderWorkspaceDir:    builderWorkspaceDir,
		BuilderTimeoutSeconds:  defaultPositiveInt(strings.TrimSpace(os.Getenv("PLATFORM_BUILDER_TIMEOUT_SECONDS")), defaultBuilderTimeoutSeconds),
	}
}

func defaultPositiveInt(value string, fallback int) int {
	parsed, err := strconv.Atoi(value)
	if err != nil || parsed <= 0 {
		return fallback
	}
	return parsed
}

func defaultString(value, fallback string) string {
	if value == "" {
		return fallback
	}
	return value
}

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
}