package config

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

// loadDotEnv loads the monorepo-root .env into the process environment.
// Existing variables (including empty ones set by tests) are never overridden.
// Missing file is a no-op — production typically injects env without a file.
func loadDotEnv() {
	if path := strings.TrimSpace(os.Getenv("DOTENV_PATH")); path != "" {
		_ = applyEnvFile(path)
		return
	}
	if root, ok := findMonorepoRoot(); ok {
		_ = applyEnvFile(filepath.Join(root, ".env"))
	}
}

func findMonorepoRoot() (string, bool) {
	cwd, err := os.Getwd()
	if err != nil {
		return "", false
	}
	dir := cwd
	for {
		if isMonorepoRoot(dir) {
			return dir, true
		}
		parent := filepath.Dir(dir)
		if parent == dir {
			return "", false
		}
		dir = parent
	}
}

func isMonorepoRoot(dir string) bool {
	api := filepath.Join(dir, "apps", "api")
	web := filepath.Join(dir, "apps", "web")
	if st, err := os.Stat(api); err != nil || !st.IsDir() {
		return false
	}
	if st, err := os.Stat(web); err != nil || !st.IsDir() {
		return false
	}
	// Prefer package.json workspaces marker when present.
	if _, err := os.Stat(filepath.Join(dir, "package.json")); err == nil {
		return true
	}
	return true
}

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

	sc := bufio.NewScanner(f)
	// Allow long values (keys, DSNs).
	sc.Buffer(make([]byte, 0, 64*1024), 1024*1024)
	for sc.Scan() {
		line := strings.TrimSpace(sc.Text())
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		if strings.HasPrefix(line, "export ") {
			line = strings.TrimSpace(strings.TrimPrefix(line, "export "))
		}
		key, val, ok := strings.Cut(line, "=")
		if !ok {
			continue
		}
		key = strings.TrimSpace(key)
		if key == "" {
			continue
		}
		if _, exists := os.LookupEnv(key); exists {
			continue
		}
		val = strings.TrimSpace(val)
		if len(val) >= 2 {
			if (val[0] == '"' && val[len(val)-1] == '"') || (val[0] == '\'' && val[len(val)-1] == '\'') {
				val = val[1 : len(val)-1]
			}
		}
		_ = os.Setenv(key, val)
	}
	return sc.Err()
}