package config

import (
	"bufio"
	"os"
	"strings"
)

// LoadDotEnvCandidates loads KEY=VALUE pairs from the first existing file in paths.
// Existing process env vars are preserved (file values only fill missing keys).
func LoadDotEnvCandidates(paths []string) {
	for _, path := range paths {
		if loadDotEnvFile(path) {
			return
		}
	}
}

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

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := strings.TrimSpace(scanner.Text())
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}

		key, value, ok := strings.Cut(line, "=")
		if !ok {
			continue
		}

		key = strings.TrimSpace(key)
		value = strings.TrimSpace(value)
		value = strings.Trim(value, `"'`)
		if key == "" {
			continue
		}

		if _, exists := os.LookupEnv(key); exists {
			continue
		}
		_ = os.Setenv(key, value)
	}

	return true
}