// This is Free Software under GNU Affero General Public License v >= 3.0
// without warranty, see README.md and license for details.
//
// SPDX-License-Identifier: AGPL-3.0-or-later
// License-Filename: LICENSES/AGPL-3.0.txt
//
// Copyright (C) 2018 by via donau
//   – Österreichische Wasserstraßen-Gesellschaft mbH
// Software engineering by Intevation GmbH
//
// Author(s):
//  * Sascha L. Teichmann <sascha.teichmann@intevation.de>

package controllers

import (
	"archive/zip"
	"bufio"
	"database/sql"
	"encoding/hex"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"sync"
	"time"

	"gemma.intevation.de/gemma/pkg/auth"
	"gemma.intevation.de/gemma/pkg/common"
	"gemma.intevation.de/gemma/pkg/config"
	"gemma.intevation.de/gemma/pkg/imports"
	"gemma.intevation.de/gemma/pkg/misc"
	"gemma.intevation.de/gemma/pkg/models"
	"github.com/gorilla/mux"
)

const (
	maxSoundingResultSize = 25 * 1024 * 1024
	soundingResultName    = "soundingresult"
)

func fetchSoundingResult(req *http.Request) (string, error) {

	// Check first if we have a token.
	if token := req.FormValue("token"); token != "" {
		if _, err := hex.DecodeString(token); err != nil {
			return "", err
		}
		dir := config.TmpDir()
		if dir == "" {
			dir = os.TempDir()
		}
		// XXX: This should hopefully be race-free enough.
		now := time.Now().Format("2006-15-04-05")
		dst := filepath.Join(dir, soundingResultName+"-"+token+"-"+now)
		if err := misc.UnmakeTempFile(token, dst); err != nil {
			return "", err
		}
	}

	return storeSoundingResult(req)
}

func storeSoundingResult(req *http.Request) (string, error) {

	// Check for direct upload.
	f, _, err := req.FormFile(soundingResultName)
	if err != nil {
		return "", err
	}
	defer f.Close()

	dir, err := ioutil.TempDir(config.TmpDir(), soundingResultName)
	if err != nil {
		return "", err
	}

	o, err := os.Create(filepath.Join(dir, "sr.zip"))
	if err != nil {
		os.RemoveAll(dir)
		return "", err
	}

	out := bufio.NewWriter(o)

	if _, err = io.Copy(out, io.LimitReader(f, maxSoundingResultSize)); err != nil {
		o.Close()
		os.RemoveAll(dir)
		return "", err
	}

	if err = out.Flush(); err != nil {
		o.Close()
		os.RemoveAll(dir)
		return "", err
	}

	return dir, nil
}

func importSoundingResult(rw http.ResponseWriter, req *http.Request) {

	dir, err := fetchSoundingResult(req)
	if err != nil {
		log.Printf("error: %v\n", err)
		http.Error(rw, "error: "+err.Error(), http.StatusInternalServerError)
		return
	}

	session, _ := auth.GetSession(req)

	jobID, err := imports.AddJob(imports.SRJobKind, session.User, dir)
	if err != nil {
		log.Printf("error: %v\n", err)
		http.Error(rw, "error: "+err.Error(), http.StatusInternalServerError)
		return
	}

	log.Printf("info: added import #%d to queue\n", jobID)

	result := struct {
		ID int64 `json:"id"`
	}{
		ID: jobID,
	}
	SendJSON(rw, http.StatusCreated, &result)
}

func loadMeta(f *zip.File) (*models.SoundingResultMeta, error) {
	r, err := f.Open()
	if err != nil {
		return nil, err
	}
	defer r.Close()
	var m models.SoundingResultMeta
	return &m, m.Decode(r)
}

func uploadSoundingResult(
	_ interface{},
	req *http.Request,
	conn *sql.Conn,
) (jr JSONResult, err error) {

	var dir string
	if dir, err = storeSoundingResult(req); err != nil {
		return
	}

	srFile := filepath.Join(dir, "sr.zip")

	var zr *zip.ReadCloser
	if zr, err = zip.OpenReader(srFile); err != nil {
		return
	}
	var once sync.Once
	closeOnce := func() { zr.Close() }
	defer once.Do(closeOnce)

	var messages []string

	var result struct {
		Token    string      `json:"token,omitempty"`
		Meta     interface{} `json:"meta,omitempty"`
		Messages []string    `json:"messages,omitempty"`
	}

	var noXYZ bool
	if noXYZ = common.FindInZIP(zr, ".xyz") == nil; noXYZ {
		messages = append(messages, "no .xyz file found.")
	}

	if mj := common.FindInZIP(zr, "meta.json"); mj == nil {
		messages = append(messages, "no 'meta.json' file found.")
	} else {
		if meta, err := loadMeta(mj); err != nil {
			messages = append(messages,
				fmt.Sprintf("'meta.json' found but invalid: %v", err))
		} else {
			errs := meta.Validate(conn, req.Context())
			for _, err := range errs {
				messages = append(messages,
					fmt.Sprintf("invalid 'meta.json': %v", err))
			}
			result.Meta = meta
		}
	}
	once.Do(closeOnce)

	code := http.StatusCreated

	// If there are no XYZ data we cant help the user anyway.
	if noXYZ {
		code = http.StatusBadRequest
		if err2 := os.RemoveAll(dir); err2 != nil {
			log.Printf("error: %v\n", err2)
		}
	} else if result.Token, err = misc.MakeTempFile(dir); err != nil {
		if err2 := os.RemoveAll(dir); err2 != nil {
			log.Printf("error: %v\n", err2)
		}
		return
	}

	result.Messages = messages

	jr = JSONResult{
		Code:   code,
		Result: &result,
	}
	return
}

func deleteSoundingUpload(rw http.ResponseWriter, req *http.Request) {
	token := mux.Vars(req)["token"]
	if _, err := hex.DecodeString(token); err != nil {
		http.Error(rw, "Invalid token", http.StatusBadRequest)
		return
	}
	if err := misc.DeleteTempFile(token); err != nil {
		http.Error(rw, fmt.Sprintf("error: %v", err), http.StatusInternalServerError)
		return
	}
	result := struct {
		Message string `json:"message"`
	}{
		Message: fmt.Sprintf("Token %s deletes.", token),
	}
	SendJSON(rw, http.StatusOK, &result)
}