package gosimpleconf

import (
	"bufio"
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"strconv"
	"strings"
)

type ConfigMap map[string]string
type FlagMap map[string]*string

func Load(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 SetupFlagOverrides(configMap ConfigMap) FlagMap {
	flagMap := make(FlagMap)
	for k, v := range configMap {
		f := flag.String(k, v, "")
		flagMap[k] = f
	}

	return flagMap
}

func ParseFlags(configMap ConfigMap, flagMap FlagMap) ConfigMap {
	flag.Parse()

	for k, v := range flagMap {
		if v != nil && len(*v) > 0 {
			configMap[k] = trimToken(*v)
		}
	}

	return configMap

}

func Bool(value string) bool {
	v, err := strconv.ParseBool(value)
	if err != nil {
		log.Printf("error parsing bool %v - %v\n", v, err)
		v = false
	}

	return v
}

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 := trimToken(split[1])

		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
}