package yatwiki3

import (
	"errors"
	"fmt"
	"html/template"
	"math/rand"
	"net/http"
	"net/url"
	"regexp"
	"strconv"
	"strings"
	"time"
)

type WikiServer struct {
	db      *WikiDB
	opts    *ServerOptions
	pageTmp *template.Template
	loc     *time.Location
	rxDiff  *regexp.Regexp
}

func NewWikiServer(opts *ServerOptions) (*WikiServer, error) {
	wdb, err := NewWikiDB(opts.DBFilePath, opts.GzipCompressionLevel)
	if err != nil {
		return nil, err
	}

	tmpl, err := template.New("yatwiki/page").Parse(pageTemplate)
	if err != nil {
		return nil, err
	}

	loc, err := time.LoadLocation(opts.Timezone)
	if err != nil {
		return nil, err
	}

	ws := WikiServer{
		db:      wdb,
		opts:    opts,
		pageTmp: tmpl,
		loc:     loc,
		rxDiff:  regexp.MustCompile(`diff/(\d+)/(\d+)`),
	}
	return &ws, nil
}

func (this *WikiServer) Close() {
	this.db.Close()
}

func (this *WikiServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Server", "YATWiki3")

	if !strings.HasPrefix(r.URL.Path, this.opts.ExpectBaseURL) {
		http.Error(w, "Bad request", 400)
		return
	}
	remainingPath := r.URL.Path[len(this.opts.ExpectBaseURL):]

	if r.Method == "GET" {
		if remainingPath == "wiki.css" {
			w.Header().Set("Content-Type", "text/css")
			content, _ := wikiCssBytes()
			w.Write(content)
			return

		} else if remainingPath == "highlight.js" {
			w.Header().Set("Content-Type", "application/javascript")
			content, _ := highlightJsBytes()
			w.Write(content)
			return

		} else if remainingPath == "favicon.ico" && len(this.opts.FaviconFilePath) > 0 {
			w.Header().Set("Content-Type", "image/x-icon")
			http.ServeFile(w, r, this.opts.FaviconFilePath)
			return

		} else if remainingPath == "download-database" {
			w.Header().Set("Content-Type", "application/octet-stream")
			w.Header().Set("Content-Disposition", `attachment; filename="database-`+fmt.Sprintf("%d", time.Now().Unix())+`.db"`)
			http.ServeFile(w, r, this.opts.DBFilePath)
			return

		} else if remainingPath == "formatting" {
			this.routeFormatting(w, r)
			return

		} else if remainingPath == "index" {
			this.routeIndex(w, r)
			return

		} else if remainingPath == "" {
			this.serveRedirect(w, this.opts.ExpectBaseURL+`view/`+url.QueryEscape(this.opts.DefaultPage))
			return

		} else if remainingPath == "random" {
			titles, err := this.db.ListTitles()
			if err != nil {
				this.serveInternalError(w, r, err)
				return
			}

			chosenArticle := titles[rand.Intn(len(titles))]
			this.serveRedirect(w, this.opts.ExpectBaseURL+`view/`+url.QueryEscape(chosenArticle))
			return

		} else if strings.HasPrefix(remainingPath, "view/") {
			articleTitle, err := url.QueryUnescape(remainingPath[len("view/"):])
			if err != nil {
				this.serveErrorMessage(w, err)
				return
			}
			this.routeView(w, r, articleTitle)
			return

		} else if strings.HasPrefix(remainingPath, "modify/") {
			articleTitle, err := url.QueryUnescape(remainingPath[len("modify/"):])
			if err != nil {
				this.serveErrorMessage(w, err)
				return
			}
			this.routeModify(w, r, articleTitle)
			return

		} else if strings.HasPrefix(remainingPath, "history/") {
			articleTitle, err := url.QueryUnescape(remainingPath[len("history/"):])
			if err != nil {
				this.serveErrorMessage(w, err)
				return
			}
			this.routeHistory(w, r, articleTitle)
			return

		} else if strings.HasPrefix(remainingPath, "raw/") {
			revId, err := strconv.Atoi(remainingPath[len("raw/"):])
			if err != nil {
				this.serveErrorMessage(w, err)
				return
			}

			this.routeRawView(w, r, revId)
			return

		} else if strings.HasPrefix(remainingPath, "archive/") {
			revId, err := strconv.Atoi(remainingPath[len("archive/"):])
			if err != nil {
				this.serveErrorMessage(w, err)
				return
			}

			this.routeArchive(w, r, revId)
			return

		} else if strings.HasPrefix(remainingPath, "recent/") {
			pageNum, err := strconv.Atoi(remainingPath[len("recent/"):])
			if err != nil {
				this.serveErrorMessage(w, err)
				return
			}

			this.routeRecentChanges(w, r, pageNum)
			return

		} else if remainingPath == "diff" {
			this.serveRedirect(w, this.opts.ExpectBaseURL+`diff/`+r.URL.Query().Get("f")+`/`+r.URL.Query().Get("t"))
			return

		} else if match := this.rxDiff.FindStringSubmatch(remainingPath); len(match) == 3 {

			fromRev, err := strconv.Atoi(match[1])
			if err != nil {
				this.serveErrorMessage(w, err)
				return
			}

			toRev, err := strconv.Atoi(match[2])
			if err != nil {
				this.serveErrorMessage(w, err)
				return
			}

			this.routeDiff(w, r, fromRev, toRev)
			return

		}

	} else if r.Method == "POST" {

		if r.URL.Path == this.opts.ExpectBaseURL+"save" {
			err := r.ParseForm()
			if err != nil {
				this.serveErrorMessage(w, err)
				return
			}

			title := r.Form.Get("pname")
			body := r.Form.Get("content")
			expectRev, err := strconv.Atoi(r.Form.Get("baserev"))
			if err != nil {
				this.serveErrorMessage(w, err)
				return
			}

			err = this.db.SaveArticle(title, Author(r), body, int64(expectRev))
			if err != nil {
				this.serveErrorMessage(w, err)
				return
			}

			this.serveRedirect(w, this.opts.ExpectBaseURL+`view/`+url.QueryEscape(title))
			return
		}

	}

	// No match? Add 'Page not found' to next session response, and redirect to homepage
	this.serveErrorMessage(w, errors.New("Page not found"))

}