package config

import (
	"fmt"
	"github.com/BurntSushi/toml"
	"github.com/zricethezav/gitleaks/options"
	"regexp"
	"strconv"
	"strings"
)

// Whitelist is struct containing items that if encountered will whitelist
// a commit/line of code that would be considered a leak.
type Whitelist struct {
	Description string
	Regex       *regexp.Regexp
	File        *regexp.Regexp
}

// entropy represents an entropy range
type entropy struct {
	P1, P2 float64
}

// Rule is a struct that contains information that is loaded from a gitleaks config.
// This struct is used in the Config struct as an array of Rules and is iterated
// over during an audit. Each rule will be checked. If a regex match is found AND
// that match is not whitelisted (globally or locally), then a leak will be appended
// to the final audit report.
type Rule struct {
	Description string
	Regex       *regexp.Regexp
	Tags        []string
	Whitelist   []Whitelist
	Entropy     []entropy
}

// Config is a composite struct of Rules and Whitelists
// Each Rule contains a description, regular expression, tags, and whitelists if available
type Config struct {
	FileRegex *regexp.Regexp
	Message   *regexp.Regexp
	Rules     []Rule
	Whitelist struct {
		Description string
		Commits     []string
		File        *regexp.Regexp
	}
}

// TomlLoader gets loaded with the values from a gitleaks toml config
// see the config in config/defaults.go for an example. TomlLoader is used
// to generate Config values (compiling regexes, etc).
type TomlLoader struct {
	Global struct {
		File    string
		Message string
	}
	Whitelist struct {
		Description string
		Commits     []string
		File        string
	}
	Rules []struct {
		Description string
		Regex       string
		Tags        []string
		Entropies   []string
		Whitelist   []struct {
			Description string
			Regex       string
			File        string
		}
	}
}

// NewConfig will create a new config struct which contains
// rules on how gitleaks will proceed with its audit.
// If no options are passed via cli then NewConfig will return
// a default config which can be seen in config.go
func NewConfig(options options.Options) (Config, error) {
	var cfg Config
	tomlLoader := TomlLoader{}

	var err error
	if options.Config != "" {
		_, err = toml.DecodeFile(options.Config, &tomlLoader)
	} else {
		_, err = toml.Decode(DefaultConfig, &tomlLoader)
	}
	if err != nil {
		return cfg, err
	}

	cfg, err = tomlLoader.Parse()
	if err != nil {
		return cfg, err
	}

	return cfg, nil
}

// Parse will parse the values set in a TomlLoader and use those values
// to create compiled regular expressions and rules used in audits
func (tomlLoader TomlLoader) Parse() (Config, error) {
	var cfg Config
	for _, rule := range tomlLoader.Rules {
		re, err := regexp.Compile(rule.Regex)
		if err != nil {
			return cfg, fmt.Errorf("problem loading config: %v", err)
		}

		// rule specific whitelists
		var whitelists []Whitelist
		for _, wl := range rule.Whitelist {
			re, err := regexp.Compile(wl.Regex)
			if err != nil {
				return cfg, fmt.Errorf("problem loading config: %v", err)
			}
			fileRe, err := regexp.Compile(wl.File)
			if err != nil {
				return cfg, fmt.Errorf("problem loading config: %v", err)
			}
			whitelists = append(whitelists, Whitelist{
				Description: wl.Description,
				File:        fileRe,
				Regex:       re,
			})
		}

		entropies, err := getEntropy(rule.Entropies)
		if err != nil {
			return cfg, err
		}

		cfg.Rules = append(cfg.Rules, Rule{
			Description: rule.Description,
			Regex:       re,
			Tags:        rule.Tags,
			Whitelist:   whitelists,
			Entropy:     entropies,
		})
	}

	// global leaks
	if tomlLoader.Global.File != "" {
		re, err := regexp.Compile(tomlLoader.Global.File)
		if err != nil {
			return cfg, fmt.Errorf("problem loading config: %v", err)
		}
		cfg.FileRegex = re
	}
	if tomlLoader.Global.Message != "" {
		re, err := regexp.Compile(tomlLoader.Global.Message)
		if err != nil {
			return cfg, fmt.Errorf("problem loading config: %v", err)
		}
		cfg.Message = re
	}

	// global whitelists
	if tomlLoader.Whitelist.File != "" {
		re, err := regexp.Compile(tomlLoader.Whitelist.File)
		if err != nil {
			return cfg, fmt.Errorf("problem loading config: %v", err)
		}
		cfg.Whitelist.File = re
	}
	cfg.Whitelist.Commits = tomlLoader.Whitelist.Commits
	cfg.Whitelist.Description = tomlLoader.Whitelist.Description

	return cfg, nil
}

// getEntropy
func getEntropy(entropyStr []string) ([]entropy, error) {
	var ranges []entropy
	for _, span := range entropyStr {
		split := strings.Split(span, "-")
		v1, err := strconv.ParseFloat(split[0], 64)
		if err != nil {
			return nil, err
		}
		v2, err := strconv.ParseFloat(split[1], 64)
		if err != nil {
			return nil, err
		}
		if v1 > v2 {
			return nil, fmt.Errorf("entropy range must be ascending")
		}
		r := entropy{P1: v1, P2: v2}
		if r.P1 > 8.0 || r.P1 < 0.0 || r.P2 > 8.0 || r.P2 < 0.0 {
			return nil, fmt.Errorf("invalid entropy ranges, must be within 0.0-8.0")
		}
		ranges = append(ranges, r)
	}
	return ranges, nil
}