package main

import (
	"bufio"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

// loadConfig reads .env and .config.json from root (if present) and sets any
// keys that aren't already in the process environment. Real env vars win.
// Recognized keys: OPENAI_API_KEY, OPENAI_BASE_URL, OPENAI_MODEL.
func loadConfig(root string) error {
	if err := loadEnvFile(filepath.Join(root, ".env")); err != nil {
		return fmt.Errorf(".env: %w", err)
	}
	if err := loadJSONConfig(filepath.Join(root, ".config.json")); err != nil {
		return fmt.Errorf(".config.json: %w", err)
	}
	return nil
}

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

	scanner := bufio.NewScanner(f)
	lineNo := 0
	for scanner.Scan() {
		lineNo++
		line := strings.TrimSpace(scanner.Text())
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		if strings.HasPrefix(line, "export ") {
			line = strings.TrimPrefix(line, "export ")
		}
		eq := strings.IndexByte(line, '=')
		if eq <= 0 {
			return fmt.Errorf("line %d: missing '='", lineNo)
		}
		key := strings.TrimSpace(line[:eq])
		val := strings.TrimSpace(line[eq+1:])
		val = unquote(val)
		setIfEmpty(key, val)
	}
	return scanner.Err()
}

func loadJSONConfig(path string) error {
	b, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return err
	}
	var m map[string]string
	if err := json.Unmarshal(b, &m); err != nil {
		return err
	}
	for k, v := range m {
		setIfEmpty(k, v)
	}
	return nil
}

func setIfEmpty(key, val string) {
	if key == "" {
		return
	}
	if _, ok := os.LookupEnv(key); ok {
		return
	}
	_ = os.Setenv(key, val)
}

func unquote(s string) string {
	if len(s) >= 2 {
		first, last := s[0], s[len(s)-1]
		if (first == '"' && last == '"') || (first == '\'' && last == '\'') {
			return s[1 : len(s)-1]
		}
	}
	return s
}