// Copyright © 2014 Steve Francia <spf@spf13.com>.
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.

// Viper is a application configuration system.
// It believes that applications can be configured a variety of ways
// via flags, ENVIRONMENT variables, configuration files retrieved
// from the file system, or a remote key/value store.

package viper

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"unicode"

	"github.com/hashicorp/hcl"
	"github.com/magiconair/properties"
	toml "github.com/pelletier/go-toml"
	"github.com/spf13/cast"
	jww "github.com/spf13/jwalterweatherman"
	"gopkg.in/yaml.v2"
)

// ConfigParseError denotes failing to parse configuration file.
type ConfigParseError struct {
	err error
}

// Error returns the formatted configuration error.
func (pe ConfigParseError) Error() string {
	return fmt.Sprintf("While parsing config: %s", pe.err.Error())
}

func insensitiviseMap(m map[string]interface{}) {
	for key, val := range m {
		lower := strings.ToLower(key)
		if key != lower {
			delete(m, key)
			m[lower] = val
			if m2, ok := val.(map[string]interface{}); ok {
				// nested map: recursively insensitivise
				insensitiviseMap(m2)
			}
		}
	}
}

func absPathify(inPath string) string {
	jww.INFO.Println("Trying to resolve absolute path to", inPath)

	if strings.HasPrefix(inPath, "$HOME") {
		inPath = userHomeDir() + inPath[5:]
	}

	if strings.HasPrefix(inPath, "$") {
		end := strings.Index(inPath, string(os.PathSeparator))
		inPath = os.Getenv(inPath[1:end]) + inPath[end:]
	}

	if filepath.IsAbs(inPath) {
		return filepath.Clean(inPath)
	}

	p, err := filepath.Abs(inPath)
	if err == nil {
		return filepath.Clean(p)
	}

	jww.ERROR.Println("Couldn't discover absolute path")
	jww.ERROR.Println(err)
	return ""
}

// Check if File / Directory Exists
func exists(path string) (bool, error) {
	_, err := v.fs.Stat(path)
	if err == nil {
		return true, nil
	}
	if os.IsNotExist(err) {
		return false, nil
	}
	return false, err
}

func stringInSlice(a string, list []string) bool {
	for _, b := range list {
		if b == a {
			return true
		}
	}
	return false
}

func userHomeDir() string {
	if runtime.GOOS == "windows" {
		home := os.Getenv("HOMEDRIVE") + os.Getenv("HOMEPATH")
		if home == "" {
			home = os.Getenv("USERPROFILE")
		}
		return home
	}
	return os.Getenv("HOME")
}

func unmarshallConfigReader(in io.Reader, c map[string]interface{}, configType string) error {
	buf := new(bytes.Buffer)
	buf.ReadFrom(in)

	switch strings.ToLower(configType) {
	case "yaml", "yml":
		if err := yaml.Unmarshal(buf.Bytes(), &c); err != nil {
			return ConfigParseError{err}
		}

	case "json":
		if err := json.Unmarshal(buf.Bytes(), &c); err != nil {
			return ConfigParseError{err}
		}

	case "hcl":
		obj, err := hcl.Parse(string(buf.Bytes()))
		if err != nil {
			return ConfigParseError{err}
		}
		if err = hcl.DecodeObject(&c, obj); err != nil {
			return ConfigParseError{err}
		}

	case "toml":
		tree, err := toml.LoadReader(buf)
		if err != nil {
			return ConfigParseError{err}
		}
		tmap := tree.ToMap()
		for k, v := range tmap {
			c[k] = v
		}

	case "properties", "props", "prop":
		var p *properties.Properties
		var err error
		if p, err = properties.Load(buf.Bytes(), properties.UTF8); err != nil {
			return ConfigParseError{err}
		}
		for _, key := range p.Keys() {
			value, _ := p.Get(key)
			// recursively build nested maps
			path := strings.Split(key, ".")
			lastKey := strings.ToLower(path[len(path)-1])
			deepestMap := deepSearch(c, path[0:len(path)-1])
			// set innermost value
			deepestMap[lastKey] = value
		}
	}

	insensitiviseMap(c)
	return nil
}

func safeMul(a, b uint) uint {
	c := a * b
	if a > 1 && b > 1 && c/b != a {
		return 0
	}
	return c
}

// parseSizeInBytes converts strings like 1GB or 12 mb into an unsigned integer number of bytes
func parseSizeInBytes(sizeStr string) uint {
	sizeStr = strings.TrimSpace(sizeStr)
	lastChar := len(sizeStr) - 1
	multiplier := uint(1)

	if lastChar > 0 {
		if sizeStr[lastChar] == 'b' || sizeStr[lastChar] == 'B' {
			if lastChar > 1 {
				switch unicode.ToLower(rune(sizeStr[lastChar-1])) {
				case 'k':
					multiplier = 1 << 10
					sizeStr = strings.TrimSpace(sizeStr[:lastChar-1])
				case 'm':
					multiplier = 1 << 20
					sizeStr = strings.TrimSpace(sizeStr[:lastChar-1])
				case 'g':
					multiplier = 1 << 30
					sizeStr = strings.TrimSpace(sizeStr[:lastChar-1])
				default:
					multiplier = 1
					sizeStr = strings.TrimSpace(sizeStr[:lastChar])
				}
			}
		}
	}

	size := cast.ToInt(sizeStr)
	if size < 0 {
		size = 0
	}

	return safeMul(uint(size), multiplier)
}

// deepSearch scans deep maps, following the key indexes listed in the
// sequence "path".
// The last value is expected to be another map, and is returned.
//
// In case intermediate keys do not exist, or map to a non-map value,
// a new map is created and inserted, and the search continues from there:
// the initial map "m" may be modified!
func deepSearch(m map[string]interface{}, path []string) map[string]interface{} {
	for _, k := range path {
		m2, ok := m[k]
		if !ok {
			// intermediate key does not exist
			// => create it and continue from there
			m3 := make(map[string]interface{})
			m[k] = m3
			m = m3
			continue
		}
		m3, ok := m2.(map[string]interface{})
		if !ok {
			// intermediate key is a value
			// => replace with a new map
			m3 = make(map[string]interface{})
			m[k] = m3
		}
		// continue search from here
		m = m3
	}
	return m
}