// This file is Free Software under the MIT License
// without warranty, see README.md and LICENSES/MIT.txt for details.
//
// SPDX-License-Identifier: MIT
//
// SPDX-FileCopyrightText: 2022 German Federal Office for Information Security (BSI) <https://www.bsi.bund.de>
// Software-Engineering: 2022 Intevation GmbH <https://intevation.de>

package main

import (
	"fmt"
	"log"
	"net/http"
	"regexp"

	"github.com/csaf-poc/csaf_distribution/v2/internal/models"
	"github.com/csaf-poc/csaf_distribution/v2/internal/options"
)

const (
	defaultWorker = 2
	defaultPreset = "mandatory"
)

type config struct {
	Directory            *string           `short:"d" long:"directory" description:"DIRectory to store the downloaded files in" value-name:"DIR" toml:"directory"`
	Insecure             bool              `long:"insecure" description:"Do not check TLS certificates from provider" toml:"insecure"`
	IgnoreSignatureCheck bool              `long:"ignoresigcheck" description:"Ignore signature check results, just warn on mismatch" toml:"ignoresigcheck"`
	Version              bool              `long:"version" description:"Display version of the binary" toml:"-"`
	Verbose              bool              `long:"verbose" short:"v" description:"Verbose output" toml:"verbose"`
	Rate                 *float64          `long:"rate" short:"r" description:"The average upper limit of https operations per second (defaults to unlimited)" toml:"rate"`
	Worker               int               `long:"worker" short:"w" description:"NUMber of concurrent downloads" value-name:"NUM" toml:"worker"`
	Range                *models.TimeRange `long:"timerange" short:"t" description:"RANGE of time from which advisories to download" value-name:"RANGE" toml:"timerange"`
	Folder               string            `long:"folder" short:"f" description:"Download into a given FOLDER" value-name:"FOLDER" toml:"folder"`
	IgnorePattern        []string          `long:"ignorepattern" short:"i" description:"Dont download files if there URLs match any of the given PATTERNs" value-name:"PATTERN" toml:"ignorepattern"`

	ExtraHeader http.Header `long:"header" short:"H" description:"One or more extra HTTP header fields" toml:"header"`

	RemoteValidator        string   `long:"validator" description:"URL to validate documents remotely" value-name:"URL" toml:"validator"`
	RemoteValidatorCache   string   `long:"validatorcache" description:"FILE to cache remote validations" value-name:"FILE" toml:"validatorcache"`
	RemoteValidatorPresets []string `long:"validatorpreset" description:"One or more PRESETS to validate remotely" value-name:"PRESETS" toml:"validatorpreset"`

	Config string `short:"c" long:"config" description:"Path to config TOML file" value-name:"TOML-FILE" toml:"-"`

	ignorePattern []*regexp.Regexp
}

// configPaths are the potential file locations of the config file.
var configPaths = []string{
	"~/.config/csaf/downloader.toml",
	"~/.csaf_downloader.toml",
	"csaf_downloader.toml",
}

// parseArgsConfig parses the command line and if need a config file.
func parseArgsConfig() ([]string, *config, error) {
	p := options.Parser[config]{
		DefaultConfigLocations: configPaths,
		ConfigLocation:         func(cfg *config) string { return cfg.Config },
		Usage:                  "[OPTIONS] domain...",
		HasVersion:             func(cfg *config) bool { return cfg.Version },
		SetDefaults: func(cfg *config) {
			cfg.Worker = defaultWorker
			cfg.RemoteValidatorPresets = []string{defaultPreset}
		},
		// Re-establish default values if not set.
		EnsureDefaults: func(cfg *config) {
			if cfg.Worker == 0 {
				cfg.Worker = defaultWorker
			}
			if cfg.RemoteValidatorPresets == nil {
				cfg.RemoteValidatorPresets = []string{defaultPreset}
			}
		},
	}
	return p.Parse()
}

// ignoreFile returns true if the given URL should not be downloaded.
func (cfg *config) ignoreURL(u string) bool {
	for _, expr := range cfg.ignorePattern {
		if expr.MatchString(u) {
			return true
		}
	}
	return false
}

// compileIgnorePatterns compiles the configure patterns to be ignored.
func (cfg *config) compileIgnorePatterns() error {
	cfg.ignorePattern = make([]*regexp.Regexp, 0, len(cfg.IgnorePattern))
	for _, pattern := range cfg.IgnorePattern {
		expr, err := regexp.Compile(pattern)
		if err != nil {
			return fmt.Errorf("invalid ignorepattern: %w", err)
		}
		if cfg.Verbose {
			log.Printf("ignore advisories containing pattern %q\n", expr)
		}
		cfg.ignorePattern = append(cfg.ignorePattern, expr)
	}
	return nil
}

// prepare prepares internal state of a loaded configuration.
func (cfg *config) prepare() error {
	return cfg.compileIgnorePatterns()
}