// SPDX-FileCopyrightText: Copyright The Miniflux Authors. All rights reserved.
// SPDX-License-Identifier: Apache-2.0

package fever // import "miniflux.app/v2/internal/fever"

import (
	"log/slog"
	"net/http"
	"strconv"
	"strings"
	"time"

	"miniflux.app/v2/internal/http/request"
	"miniflux.app/v2/internal/http/response"
	"miniflux.app/v2/internal/integration"
	"miniflux.app/v2/internal/mediaproxy"
	"miniflux.app/v2/internal/model"
	"miniflux.app/v2/internal/storage"
)

// NewHandler returns an http.Handler for Fever API calls.
func NewHandler(store *storage.Storage) http.Handler {
	h := &feverHandler{store: store}
	return http.HandlerFunc(h.serve)
}

type feverHandler struct {
	store *storage.Storage
}

func (h *feverHandler) serve(w http.ResponseWriter, r *http.Request) {
	switch {
	case request.HasQueryParam(r, "groups"):
		h.handleGroups(w, r)
	case request.HasQueryParam(r, "feeds"):
		h.handleFeeds(w, r)
	case request.HasQueryParam(r, "favicons"):
		h.handleFavicons(w, r)
	case request.HasQueryParam(r, "unread_item_ids"):
		h.handleUnreadItems(w, r)
	case request.HasQueryParam(r, "saved_item_ids"):
		h.handleSavedItems(w, r)
	case request.HasQueryParam(r, "items"):
		h.handleItems(w, r)
	case r.FormValue("mark") == "item":
		h.handleWriteItems(w, r)
	case r.FormValue("mark") == "feed":
		h.handleWriteFeeds(w, r)
	case r.FormValue("mark") == "group":
		h.handleWriteGroups(w, r)
	default:
		response.JSON(w, r, newBaseResponse())
	}
}

/*
A request with the groups argument will return two additional members:

	groups contains an array of group objects
	feeds_groups contains an array of feeds_group objects

A group object has the following members:

	id (positive integer)
	title (utf-8 string)

The feeds_group object is documented under “Feeds/Groups Relationships.”

The “Kindling” super group is not included in this response and is composed of all feeds with
an is_spark equal to 0.

The “Sparks” super group is not included in this response and is composed of all feeds with an
is_spark equal to 1.
*/
func (h *feverHandler) handleGroups(w http.ResponseWriter, r *http.Request) {
	userID := request.UserID(r)
	slog.Debug("[Fever] Fetching groups",
		slog.Int64("user_id", userID),
	)

	categories, err := h.store.Categories(userID)
	if err != nil {
		response.JSONServerError(w, r, err)
		return
	}

	feeds, err := h.store.Feeds(userID)
	if err != nil {
		response.JSONServerError(w, r, err)
		return
	}

	var result groupsResponse
	for _, category := range categories {
		result.Groups = append(result.Groups, group{ID: category.ID, Title: category.Title})
	}

	result.FeedsGroups = buildFeedGroups(feeds)
	result.SetCommonValues()
	response.JSON(w, r, result)
}

/*
A request with the feeds argument will return two additional members:

	feeds contains an array of group objects
	feeds_groups contains an array of feeds_group objects

A feed object has the following members:

	id (positive integer)
	favicon_id (positive integer)
	title (utf-8 string)
	url (utf-8 string)
	site_url (utf-8 string)
	is_spark (boolean integer)
	last_updated_on_time (Unix timestamp/integer)

The feeds_group object is documented under “Feeds/Groups Relationships.”

The “All Items” super feed is not included in this response and is composed of all items from all feeds
that belong to a given group. For the “Kindling” super group and all user created groups the items
should be limited to feeds with an is_spark equal to 0.

For the “Sparks” super group the items should be limited to feeds with an is_spark equal to 1.
*/
func (h *feverHandler) handleFeeds(w http.ResponseWriter, r *http.Request) {
	userID := request.UserID(r)
	slog.Debug("[Fever] Fetching feeds",
		slog.Int64("user_id", userID),
	)

	feeds, err := h.store.Feeds(userID)
	if err != nil {
		response.JSONServerError(w, r, err)
		return
	}

	var result feedsResponse
	result.Feeds = make([]feed, 0, len(feeds))
	for _, f := range feeds {
		subscription := feed{
			ID:          f.ID,
			Title:       f.Title,
			URL:         f.FeedURL,
			SiteURL:     f.SiteURL,
			IsSpark:     0,
			LastUpdated: f.CheckedAt.Unix(),
		}

		if f.Icon != nil {
			subscription.FaviconID = f.Icon.IconID
		}

		result.Feeds = append(result.Feeds, subscription)
	}

	result.FeedsGroups = buildFeedGroups(feeds)
	result.SetCommonValues()
	response.JSON(w, r, result)
}

/*
A request with the favicons argument will return one additional member:

	favicons contains an array of favicon objects

A favicon object has the following members:

	id (positive integer)
	data (base64 encoded image data; prefixed by image type)

An example data value:

	image/gif;base64,R0lGODlhAQABAIAAAObm5gAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==

The data member of a favicon object can be used with the data: protocol to embed an image in CSS or HTML.
A PHP/HTML example:

	echo '<img src="data:'.$favicon['data'].'">';
*/
func (h *feverHandler) handleFavicons(w http.ResponseWriter, r *http.Request) {
	userID := request.UserID(r)
	slog.Debug("[Fever] Fetching favicons",
		slog.Int64("user_id", userID),
	)

	icons, err := h.store.Icons(userID)
	if err != nil {
		response.JSONServerError(w, r, err)
		return
	}

	var result faviconsResponse
	for _, i := range icons {
		result.Favicons = append(result.Favicons, favicon{
			ID:   i.ID,
			Data: i.DataURL(),
		})
	}

	result.SetCommonValues()
	response.JSON(w, r, result)
}

/*
A request with the items argument will return two additional members:

	items contains an array of item objects
	total_items contains the total number of items stored in the database (added in API version 2)

An item object has the following members:

	id (positive integer)
	feed_id (positive integer)
	title (utf-8 string)
	author (utf-8 string)
	html (utf-8 string)
	url (utf-8 string)
	is_saved (boolean integer)
	is_read (boolean integer)
	created_on_time (Unix timestamp/integer)

Most servers won’t have enough memory allocated to PHP to dump all items at once.
Three optional arguments control determine the items included in the response.

	Use the since_id argument with the highest id of locally cached items to request 50 additional items.
	Repeat until the items array in the response is empty.

	Use the max_id argument with the lowest id of locally cached items (or 0 initially) to request 50 previous items.
	Repeat until the items array in the response is empty. (added in API version 2)

	Use the with_ids argument with a comma-separated list of item ids to request (a maximum of 50) specific items.
	(added in API version 2)
*/
func (h *feverHandler) handleItems(w http.ResponseWriter, r *http.Request) {
	var result itemsResponse

	userID := request.UserID(r)

	builder := h.store.NewEntryQueryBuilder(userID).
		WithLimit(50)

	switch {
	case request.HasQueryParam(r, "since_id"):
		sinceID := request.QueryInt64Param(r, "since_id", 0)
		if sinceID > 0 {
			slog.Debug("[Fever] Fetching items since a given date",
				slog.Int64("user_id", userID),
				slog.Int64("since_id", sinceID),
			)
			builder.AfterEntryID(sinceID)
			builder.WithSorting("id", "ASC")
		}
	case request.HasQueryParam(r, "max_id"):
		maxID := request.QueryInt64Param(r, "max_id", 0)
		if maxID == 0 {
			slog.Debug("[Fever] Fetching most recent items",
				slog.Int64("user_id", userID),
			)
			builder.WithSorting("id", "DESC")
		} else if maxID > 0 {
			slog.Debug("[Fever] Fetching items before a given item ID",
				slog.Int64("user_id", userID),
				slog.Int64("max_id", maxID),
			)
			builder.BeforeEntryID(maxID)
			builder.WithSorting("id", "DESC")
		}
	case request.HasQueryParam(r, "with_ids"):
		csvItemIDs := request.QueryStringParam(r, "with_ids", "")
		if csvItemIDs != "" {
			var itemIDs []int64

			for strItemID := range strings.SplitSeq(csvItemIDs, ",") {
				strItemID = strings.TrimSpace(strItemID)
				itemID, _ := strconv.ParseInt(strItemID, 10, 64)
				itemIDs = append(itemIDs, itemID)
			}

			builder.WithEntryIDs(itemIDs...)
		}
	default:
		slog.Debug("[Fever] Fetching oldest items",
			slog.Int64("user_id", userID),
		)
	}

	entries, err := builder.GetEntries()
	if err != nil {
		response.JSONServerError(w, r, err)
		return
	}

	result.Total, err = h.store.NewEntryQueryBuilder(userID).
		CountEntries()
	if err != nil {
		response.JSONServerError(w, r, err)
		return
	}

	result.Items = make([]item, 0, len(entries))
	for _, entry := range entries {
		isRead := 0
		if entry.Status == model.EntryStatusRead {
			isRead = 1
		}

		isSaved := 0
		if entry.Starred {
			isSaved = 1
		}

		result.Items = append(result.Items, item{
			ID:        entry.ID,
			FeedID:    entry.FeedID,
			Title:     entry.Title,
			Author:    entry.Author,
			HTML:      mediaproxy.RewriteDocumentWithAbsoluteProxyURL(entry.Content),
			URL:       entry.URL,
			IsSaved:   isSaved,
			IsRead:    isRead,
			CreatedAt: entry.Date.Unix(),
		})
	}

	result.SetCommonValues()
	response.JSON(w, r, result)
}

/*
The unread_item_ids and saved_item_ids arguments can be used to keep your local cache synced
with the remote Fever installation.

A request with the unread_item_ids argument will return one additional member:

	unread_item_ids (string/comma-separated list of positive integers)
*/
func (h *feverHandler) handleUnreadItems(w http.ResponseWriter, r *http.Request) {
	userID := request.UserID(r)
	slog.Debug("[Fever] Fetching unread items",
		slog.Int64("user_id", userID),
	)

	rawEntryIDs, err := h.store.NewEntryQueryBuilder(userID).
		WithStatuses(model.EntryStatusUnread).
		GetEntryIDs()
	if err != nil {
		response.JSONServerError(w, r, err)
		return
	}

	itemIDs := make([]string, 0, len(rawEntryIDs))
	for _, entryID := range rawEntryIDs {
		itemIDs = append(itemIDs, strconv.FormatInt(entryID, 10))
	}

	var result unreadResponse
	result.ItemIDs = strings.Join(itemIDs, ",")
	result.SetCommonValues()
	response.JSON(w, r, result)
}

/*
The unread_item_ids and saved_item_ids arguments can be used to keep your local cache synced
with the remote Fever installation.

	A request with the saved_item_ids argument will return one additional member:

	saved_item_ids (string/comma-separated list of positive integers)
*/
func (h *feverHandler) handleSavedItems(w http.ResponseWriter, r *http.Request) {
	userID := request.UserID(r)
	slog.Debug("[Fever] Fetching saved items",
		slog.Int64("user_id", userID),
	)

	entryIDs, err := h.store.NewEntryQueryBuilder(userID).
		WithStarred(true).
		GetEntryIDs()
	if err != nil {
		response.JSONServerError(w, r, err)
		return
	}

	itemsIDs := make([]string, 0, len(entryIDs))
	for _, entryID := range entryIDs {
		itemsIDs = append(itemsIDs, strconv.FormatInt(entryID, 10))
	}

	result := &savedResponse{ItemIDs: strings.Join(itemsIDs, ",")}
	result.SetCommonValues()
	response.JSON(w, r, result)
}

/*
mark=item
as=? where ? is replaced with read, saved or unsaved
id=? where ? is replaced with the id of the item to modify
*/
func (h *feverHandler) handleWriteItems(w http.ResponseWriter, r *http.Request) {
	userID := request.UserID(r)
	slog.Debug("[Fever] Receiving mark=item call",
		slog.Int64("user_id", userID),
	)

	entryID := request.FormInt64Value(r, "id")
	if entryID <= 0 {
		return
	}

	entry, err := h.store.NewEntryQueryBuilder(userID).
		WithEntryIDs(entryID).
		GetEntry()
	if err != nil {
		response.JSONServerError(w, r, err)
		return
	}

	if entry == nil {
		slog.Debug("[Fever] Entry not found",
			slog.Int64("user_id", userID),
			slog.Int64("entry_id", entryID),
		)
		response.JSON(w, r, newBaseResponse())
		return
	}

	switch r.FormValue("as") {
	case "read":
		slog.Debug("[Fever] Mark entry as read",
			slog.Int64("user_id", userID),
			slog.Int64("entry_id", entryID),
		)
		h.store.SetEntriesStatus(userID, []int64{entryID}, model.EntryStatusRead)
	case "unread":
		slog.Debug("[Fever] Mark entry as unread",
			slog.Int64("user_id", userID),
			slog.Int64("entry_id", entryID),
		)
		h.store.SetEntriesStatus(userID, []int64{entryID}, model.EntryStatusUnread)
	case "saved":
		slog.Debug("[Fever] Mark entry as saved",
			slog.Int64("user_id", userID),
			slog.Int64("entry_id", entryID),
		)
		if err := h.store.ToggleStarred(userID, entryID); err != nil {
			response.JSONServerError(w, r, err)
			return
		}

		settings, err := h.store.Integration(userID)
		if err != nil {
			response.JSONServerError(w, r, err)
			return
		}

		go func() {
			integration.SendEntry(entry, settings)
		}()
	case "unsaved":
		slog.Debug("[Fever] Mark entry as unsaved",
			slog.Int64("user_id", userID),
			slog.Int64("entry_id", entryID),
		)
		if err := h.store.ToggleStarred(userID, entryID); err != nil {
			response.JSONServerError(w, r, err)
			return
		}
	}

	response.JSON(w, r, newBaseResponse())
}

/*
mark=feed
as=read
id=? where ? is replaced with the id of the feed or group to modify
before=? where ? is replaced with the Unix timestamp of the the local client’s most recent items API request
*/
func (h *feverHandler) handleWriteFeeds(w http.ResponseWriter, r *http.Request) {
	userID := request.UserID(r)
	feedID := request.FormInt64Value(r, "id")
	before := time.Unix(request.FormInt64Value(r, "before"), 0)

	slog.Debug("[Fever] Mark feed as read before a given date",
		slog.Int64("user_id", userID),
		slog.Int64("feed_id", feedID),
		slog.Time("before_ts", before),
	)

	if feedID <= 0 {
		return
	}

	if err := h.store.MarkFeedAsRead(userID, feedID, before); err != nil {
		response.JSONServerError(w, r, err)
		return
	}

	response.JSON(w, r, newBaseResponse())
}

/*
mark=group
as=read
id=? where ? is replaced with the id of the feed or group to modify
before=? where ? is replaced with the Unix timestamp of the the local client’s most recent items API request
*/
func (h *feverHandler) handleWriteGroups(w http.ResponseWriter, r *http.Request) {
	userID := request.UserID(r)
	groupID := request.FormInt64Value(r, "id")

	if groupID < 0 {
		return
	}

	var err error

	if groupID == 0 {
		err = h.store.MarkAllAsRead(userID)
		slog.Debug("[Fever] Mark all items as read",
			slog.Int64("user_id", userID),
		)
	} else {
		before := time.Unix(request.FormInt64Value(r, "before"), 0)
		err = h.store.MarkCategoryAsRead(userID, groupID, before)
		slog.Debug("[Fever] Mark group as read before a given date",
			slog.Int64("user_id", userID),
			slog.Int64("group_id", groupID),
			slog.Time("before_ts", before),
		)
	}

	if err != nil {
		response.JSONServerError(w, r, err)
		return
	}

	response.JSON(w, r, newBaseResponse())
}

/*
A feeds_group object has the following members:

	group_id (positive integer)
	feed_ids (string/comma-separated list of positive integers)
*/
func buildFeedGroups(feeds model.Feeds) []feedsGroups {
	feedsGroupedByCategory := make(map[int64][]string, len(feeds))
	for _, feed := range feeds {
		feedsGroupedByCategory[feed.Category.ID] = append(feedsGroupedByCategory[feed.Category.ID], strconv.FormatInt(feed.ID, 10))
	}

	result := make([]feedsGroups, 0, len(feedsGroupedByCategory))
	for categoryID, feedIDs := range feedsGroupedByCategory {
		result = append(result, feedsGroups{
			GroupID: categoryID,
			FeedIDs: strings.Join(feedIDs, ","),
		})
	}

	return result
}
