package gosimpleconf

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"strings"
)

type ConfigMap map[string]string

func Load(filename string) (ConfigMap, error) {
	return ReadFile(filename)
}

func ReadFile(filename string) (ConfigMap, error) {
	var err error

	file, err := os.Open(filename)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	parsedMap, err := parseFile(file)
	if err != nil {
		return nil, err
	}

	return parsedMap, nil
}

func WriteFile(filename string, configMap ConfigMap) error {
	file, err := os.Create(filename)
	if err != nil {
		return err
	}
	defer file.Close()

	for k, v := range configMap {
		fmt.Fprintf(file, "%s = %s\n", k, v)
	}

	return nil
}

func parseFile(config io.Reader) (ConfigMap, error) {
	var err error
	parsedMap := make(ConfigMap)

	scanner := bufio.NewScanner(config)
	for scanner.Scan() {
		line := scanner.Text()
		trimmed := strings.TrimSpace(line)
		if len(trimmed) == 0 {
			// ignore empty lines
			continue
		}

		if trimmed[0] == '#' {
			// ignore comments
			continue
		}

		split := strings.Split(trimmed, "=")
		if len(split) < 2 {
			return nil, fmt.Errorf("failed to parse config line: %v", trimmed)
		}

		key := trimToken(split[0])

		value := strings.Join(split[1:], "=") // Re-add any ='s that were part of the value
		value = trimToken(value)

		parsedMap[key] = value
	}

	if err = scanner.Err(); err != nil {
		return nil, err
	}

	return parsedMap, nil
}

func trimToken(value string) string {
	// Trim off whitespace
	v := strings.TrimSpace(value)

	// Trim off any surrounding quotes, everything is a string anyway
	v = strings.TrimPrefix(v, "\"")
	v = strings.TrimSuffix(v, "\"")

	return v
}