package main

import (
	"crypto/tls"
	"errors"
	"io/ioutil"
	"log"
	"net/url"
	"os"
	"regexp"
	"strconv"
	"strings"

	"code.rocketnine.space/tslocum/gmitohtml/pkg/gmitohtml"
	"github.com/kballard/go-shellquote"
	"github.com/yookoala/gofast"
	"gopkg.in/yaml.v2"
)

type pathConfig struct {
	// Path to match
	Path string

	// Resource to serve
	Root     string
	Command  string
	Proxy    string
	Redirect string

	// Cache duration
	Cache string

	// FastCGI server address
	FastCGI string

	// Serve hidden files and directories
	Hidden bool

	// Request input
	Input string

	// Language
	Lang string

	// List directory
	List bool

	// Log file
	Log string

	// Request sensitive input
	SensitiveInput string

	// Follow symbolic links
	SymLinks bool

	// Content type
	Type string

	r     *regexp.Regexp
	cmd   []string
	cache int64
}

type hostConfig struct {
	Cert  string
	Key   string
	Paths []*pathConfig

	// Custom CSS styles. If specified, it will be used for all paths in that host/domain.
	StyleSheet string

	cert *tls.Certificate
	css  []byte
}

type serverConfig struct {
	Listen       string
	Types        map[string]string
	ShowImages   bool
	Hosts        map[string]*hostConfig
	DisableHTTPS bool
	DisableSize  bool
	SaneEOL      bool

	hostname  string
	port      int
	fcgiPools map[string]gofast.ConnFactory
}

const cacheUnset = -1965

var config *serverConfig

func readconfig(configPath string) error {
	if configPath == "" {
		return errors.New("file unspecified")
	}

	if _, err := os.Stat(configPath); os.IsNotExist(err) {
		return errors.New("file not found")
	}

	configData, err := ioutil.ReadFile(configPath)
	if err != nil {
		return err
	}

	var newConfig *serverConfig
	err = yaml.Unmarshal(configData, &newConfig)
	if err != nil {
		return err
	}
	config = newConfig

	if config.Listen == "" {
		log.Fatal("listen address must be specified")
	}

	if config.Types == nil {
		config.Types = make(map[string]string)
	}

	if config.SaneEOL {
		newLine = "\n"
	} else {
		newLine = "\r\n"
	}

	listenRe := regexp.MustCompile("(.*):([0-9]+)$")
	if !listenRe.MatchString(config.Listen) {
		config.hostname = config.Listen
		config.Listen += ":1965"
	} else {
		config.hostname = listenRe.ReplaceAllString(config.Listen, "$1")
		config.port, err = strconv.Atoi(listenRe.ReplaceAllString(config.Listen, "$2"))
		if err != nil {
			log.Fatalf("invalid port specified: %s", err)
		}
	}

	// Default content types
	if config.Types[".htm"] == "" {
		config.Types[".htm"] = htmlType
	}
	if config.Types[".html"] == "" {
		config.Types[".html"] = htmlType
	}
	if config.Types[".gmi"] == "" {
		config.Types[".gmi"] = geminiType
	}
	if config.Types[".gemini"] == "" {
		config.Types[".gemini"] = geminiType
	}

	gmitohtml.Config.ConvertImages = config.ShowImages

	defaultHost := config.Hosts["default"]
	delete(config.Hosts, "default")

	config.fcgiPools = make(map[string]gofast.ConnFactory)
	for hostname, host := range config.Hosts {
		hostname = strings.ToLower(hostname)

		if defaultHost != nil {
			if host.Cert == "" {
				host.Cert = defaultHost.Cert
			}
			if host.Key == "" {
				host.Key = defaultHost.Key
			}
			if len(defaultHost.Paths) == 1 {
				defaultPath := defaultHost.Paths[0]
				for _, serve := range host.Paths {
					// Resources
					if defaultPath.Root != "" && serve.Root == "" {
						serve.Root = defaultPath.Root
					} else if defaultPath.Command != "" && serve.Command == "" {
						serve.Command = defaultPath.Command
					} else if defaultPath.Proxy != "" && serve.Proxy == "" {
						serve.Proxy = defaultPath.Proxy
					}
					// Attributes
					if defaultPath.Cache != "" && serve.Cache == "" {
						serve.Cache = defaultPath.Cache
					}
					if defaultPath.FastCGI != "" && serve.FastCGI == "" {
						serve.FastCGI = defaultPath.FastCGI
					}
					if defaultPath.Hidden {
						serve.Hidden = defaultPath.Hidden
					}
					if defaultPath.Lang != "" && serve.Lang == "" {
						serve.Lang = defaultPath.Lang
					}
					if defaultPath.List {
						serve.List = defaultPath.List
					}
					if defaultPath.Log != "" && serve.Log == "" {
						serve.Log = defaultPath.Log
					}
					if defaultPath.SymLinks {
						serve.SymLinks = defaultPath.SymLinks
					}
				}
			} else if len(defaultHost.Paths) > 1 {
				log.Fatal("only one path may be defined for the default host")
			}
		}

		if host.Cert == "" || host.Key == "" {
			log.Fatal("a certificate must be specified for each domain (gemini requires TLS for all connections)")
		}

		cert, err := tls.LoadX509KeyPair(host.Cert, host.Key)
		if err != nil {
			log.Fatalf("failed to load certificate: %s", err)
		}
		host.cert = &cert

		// Custom CSS stylesheets are precached in customCSS and used on HTTPS requests.
		if host.StyleSheet != "" {
			_, err := os.Stat(host.StyleSheet)
			if os.IsNotExist(err) {
				log.Printf("error: stylesheet '%s' not found", host.StyleSheet)
			} else {
				host.css, err = ioutil.ReadFile(host.StyleSheet)
				if err != nil {
					host.css = nil
					log.Printf("error: failed to read stylesheet %s: %s", host.StyleSheet, err)
				}
			}
		}

		for _, serve := range host.Paths {
			if serve.Path == "" {
				log.Fatal("a path must be specified in each serve entry")
			}
			if serve.Path[0] == '^' {
				serve.r = regexp.MustCompile(serve.Path)
			}

			var resources int
			if serve.Root != "" {
				resources++
			}
			if serve.Command != "" {
				resources++
			}
			if serve.Proxy != "" {
				resources++
			}
			if serve.Redirect != "" {
				resources++
			}
			if resources == 0 {
				log.Fatalf("a resource must specified for path %s%s", hostname, serve.Path)
			} else if resources > 1 {
				log.Fatalf("only one resource (root, command, proxy or redirect) may specified for path %s%s", hostname, serve.Path)
			}

			serve.cache = cacheUnset
			if serve.Cache != "" {
				serve.cache, err = strconv.ParseInt(serve.Cache, 10, 64)
				if err != nil {
					log.Fatalf("failed to parse cache duration for path %s: %s", serve.Path, err)
				}
			}

			if serve.Command != "" {
				serve.cmd, err = shellquote.Split(serve.Command)
				if err != nil {
					log.Fatalf("failed to parse command %s: %s", serve.cmd, err)
				}
			} else if serve.FastCGI != "" {
				if serve.Root == "" {
					log.Fatalf("root must be specified to use fastcgi resource %s of path %s%s", serve.FastCGI, hostname, serve.Path)
				}

				if config.fcgiPools[serve.FastCGI] == nil {
					f, err := url.Parse(serve.FastCGI)
					if err != nil {
						log.Fatalf("failed to parse fastcgi resource %s: %s", serve.FastCGI, err)
					}

					config.fcgiPools[serve.FastCGI] = gofast.SimpleConnFactory(f.Scheme, f.Host+f.Path)
				}
			}
		}
	}

	return nil
}