package main

import (
	"context"
	"flag"
	"io"
	"mime"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"strings"
	"time"

	"git.icedream.tech/icedream/oneandone-billing-mailer/pkg/api"
	"git.icedream.tech/icedream/oneandone-billing-mailer/pkg/appcontext"
	"git.icedream.tech/icedream/oneandone-billing-mailer/pkg/auth"
	"git.icedream.tech/icedream/oneandone-billing-mailer/pkg/auth/authcache"
	"git.icedream.tech/icedream/oneandone-billing-mailer/pkg/auth/authcache/fileauthcache"
	"git.icedream.tech/icedream/oneandone-billing-mailer/pkg/backend"
	"git.icedream.tech/icedream/oneandone-billing-mailer/pkg/environment"
	"github.com/go-logr/logr"
	"github.com/go-logr/zapr"
	"go.uber.org/zap"
	"golang.org/x/oauth2"
)

const (
	// webviewDebug toggles the debug mode in the Webview library.
	webviewDebug = false

	// apiDebug toggles the debug mode in the OpenAPI client.
	apiDebug = false
)

// dateFormat is the format used to pass dates to the 1&1 API
const dateFormat = "2006-01-02"

// main is the main entrypoint.
func main() {
	ctx := context.Background()

	// load logger
	zapLogger, err := zap.NewDevelopment()
	if err != nil {
		os.Stderr.WriteString("Could not initialize zap logger\n")
		os.Exit(1)
		return
	}
	generalLog := zapr.NewLogger(zapLogger)
	ctx = logr.NewContext(ctx, generalLog)
	log := generalLog.WithName("app")

	// parse cmdline
	flag.Parse()

	// initialize oauth stuff for API
	oauth, err := auth.NewOAuthFromEnvironment(ctx)
	if err != nil {
		log.Error(err, "Failed to initialize central login helper")
		return
	}

	// Try and get an initial token first
	tokenCache := fileauthcache.NewFileAuthCache("token.json")
	token, err := tokenCache.Fetch()
	if err != nil {
		log.Error(err, "Failed to fetch token from cache")
		return
	}
	if token == nil {
		// We need to fetch an initial token
		tokenSource, err := oauth.TokenSource(nil, requestUserConsentFunc(ctx))
		if err != nil {
			log.Error(err, "Failed to set up OAuth token source")
			return
		}
		cacheTokenSource := authcache.NewCacheTokenSource(ctx, tokenCache, tokenSource)
		token, err = cacheTokenSource.Token()
		if err != nil {
			log.Error(err, "Failed to fetch initial token")
			return
		}
	}

	// Set up new token source only for refreshing
	tokenSource, err := oauth.TokenSource(token, nil)
	if err != nil {
		log.Error(err, "Failed to set up OAuth token source")
		return
	}
	cacheTokenSource := authcache.NewCacheTokenSource(ctx, tokenCache, tokenSource)

	reuseTokenSource := oauth2.ReuseTokenSource(token, cacheTokenSource)

	client := oauth2.NewClient(ctx, reuseTokenSource)
	client.Transport = backend.BackendRequestTransport(client.Transport)

	// MSSA invoice requests from here

	appctx, err := appcontext.GetEnvironmentContext()
	if err != nil {
		log.Error(err, "Failed to fetch app env context")
		return
	}
	mssaBaseURL, err := appctx.MSSA.BaseURL()
	if err != nil {
		log.Error(err, "Failed to parse MSSA base URL")
		return
	}

	auth := context.WithValue(ctx, api.ContextOAuth2, reuseTokenSource)

	apiConfig := api.NewConfiguration()
	apiConfig.HTTPClient = client
	apiConfig.Debug = apiDebug
	apiConfig.UserAgent = environment.UserAgent()

	apiClient := api.NewAPIClient(apiConfig)

	now := time.Now()
	thisMonthStartDate := now.
		// go to first day of this month
		AddDate(0, 0, 1-now.Day())
	nextMonthStartDate := thisMonthStartDate.
		// add 1 month
		AddDate(0, 1, 0)

	apiReq := apiClient.InvoicesApi.GetInvoicesInInterval(auth,
		thisMonthStartDate.Format(dateFormat),
		nextMonthStartDate.Format(dateFormat)).
		PerPage(1)
	apiResp, resp, err := apiReq.Page(1).Execute()
	if err != nil {
		panic(err)
	}
	if resp.StatusCode != http.StatusOK {
		panic(resp.Status)
	}
	for _, invoice := range apiResp.GetInvoice() {
		// skip entries without invoice document
		doc := invoice.Links.InvoiceDocument
		if doc == nil {
			continue
		}

		ext := ".pdf"
		if doc.Type != nil {
			exts, err := mime.ExtensionsByType(*doc.Type)
			if err != nil {
				log.V(1).Error(err, "Failed to fetch extensions for type",
					"type", *doc.Type)
			} else if len(exts) > 0 {
				ext = exts[0]
			}
		}
		// make sure extension starts with dot
		if !strings.HasPrefix(ext, ".") {
			ext = "." + ext
		}

		title := "Rechnung"
		if doc.Title != nil {
			title = *doc.Title
		}
		fileName := filepath.Clean(title) + ext

		u, err := url.Parse(doc.Href)
		if err != nil {
			log.V(1).Error(err, "Failed to parse invoice document hyperlink reference, skipping",
				"url", doc.Href)
			continue
		}
		u = mssaBaseURL.ResolveReference(u)

		// open PDF on server
		resp, err := apiClient.GetConfig().HTTPClient.Get(u.String())
		if err != nil {
			log.Error(err, "Invoice PDF download request failed, skipping",
				"fileName", fileName)
			continue
		}
		if resp.StatusCode != http.StatusOK {
			resp.Body.Close()
			log.Error(err, "Unexpected status code for invoice PDF download request, skipping",
				"fileName", fileName,
				"statusCode", resp.StatusCode)
			continue
		}

		// write PDF to file as we download
		f, err := os.Create(fileName)
		if err != nil {
			resp.Body.Close()
			log.Error(err, "Could not create invoice PDF",
				"fileName", fileName)
			continue
		}
		_, err = io.Copy(f, resp.Body)
		resp.Body.Close()
		if err != nil {
			os.Remove(f.Name())
			log.Error(err, "Could not write to invoice PDF",
				"fileName", fileName)
		}
		err = f.Close()
		if err != nil {
			os.Remove(f.Name())
			log.Error(err, "Could not complete writing to invoice PDF",
				"fileName", fileName)
		}
	}
}