/*
Copyright 2020 Bruno Windels <bruno@windels.cloud>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

import {MEGOLM_ALGORITHM} from "../e2ee/common.js";


function applyTimelineEntries(data, timelineEntries, isInitialSync, canMarkUnread, ownUserId) {
    if (timelineEntries.length) {
        data = timelineEntries.reduce((data, entry) => {
            return processTimelineEvent(data, entry,
                isInitialSync, canMarkUnread, ownUserId);
        }, data);
    }
    return data;
}


function applySyncResponse(data, roomResponse, membership, ownUserId) {
    if (roomResponse.summary) {
        data = updateSummary(data, roomResponse.summary);
    }
    let needKickDetails = false;
    if (membership !== data.membership) {
        data = data.cloneIfNeeded();
        data.membership = membership;
        needKickDetails = membership === "leave" || membership === "ban";
    }
    if (roomResponse.account_data) {
        data = roomResponse.account_data.events.reduce(processRoomAccountData, data);
    }
    const stateEvents = roomResponse?.state?.events;
    // state comes before timeline
    if (Array.isArray(stateEvents)) {
        data = stateEvents.reduce((data, event) => {
            if (needKickDetails) {
                data = findKickDetails(data, event, ownUserId);
            }
            return processStateEvent(data, event, ownUserId, needKickDetails);
        }, data);
    }
    const timelineEvents = roomResponse?.timeline?.events;
    // process state events in timeline
    // non-state events are handled by applyTimelineEntries
    // so decryption is handled properly
    if (Array.isArray(timelineEvents)) {
        data = timelineEvents.reduce((data, event) => {
            if (typeof event.state_key === "string") {
                if (needKickDetails) {
                    data = findKickDetails(data, event, ownUserId);
                }
                return processStateEvent(data, event);
            }
            return data;
        }, data);
    }
    const unreadNotifications = roomResponse.unread_notifications;
    if (unreadNotifications) {
        data = processNotificationCounts(data, unreadNotifications);
    }

    return data;
}

function processNotificationCounts(data, unreadNotifications) {
    const highlightCount = unreadNotifications.highlight_count || 0;
    if (highlightCount !== data.highlightCount) {
        data = data.cloneIfNeeded();
        data.highlightCount = highlightCount;
    }
    const notificationCount = unreadNotifications.notification_count;
    if (notificationCount !== data.notificationCount) {
        data = data.cloneIfNeeded();
        data.notificationCount = notificationCount;
    }
    return data;
} 

function processRoomAccountData(data, event) {
    if (event?.type === "m.tag") {
        let tags = event?.content?.tags;
        if (!tags || Array.isArray(tags) || typeof tags !== "object") {
            tags = null;
        }
        data = data.cloneIfNeeded();
        data.tags = tags;
    }
    return data;
}

export function processStateEvent(data, event) {
    if (event.type === "m.room.encryption") {
        const algorithm = event.content?.algorithm;
        if (!data.encryption && algorithm === MEGOLM_ALGORITHM) {
            data = data.cloneIfNeeded();
            data.encryption = event.content;
        }
    } else if (event.type === "m.room.name") {
        const newName = event.content?.name;
        if (newName !== data.name) {
            data = data.cloneIfNeeded();
            data.name = newName;
        }
    } else if (event.type === "m.room.avatar") {
        const newUrl = event.content?.url;
        if (newUrl !== data.avatarUrl) {
            data = data.cloneIfNeeded();
            data.avatarUrl = newUrl;
        }
    } else if (event.type === "m.room.canonical_alias") {
        const content = event.content;
        data = data.cloneIfNeeded();
        data.canonicalAlias = content.alias;
    }
    return data;
}

function findKickDetails(data, event, ownUserId) {
    if (event.type === "m.room.member") {
        // did we get kicked?
        if (event.state_key === ownUserId && event.sender !== event.state_key) {
            data = data.cloneIfNeeded();
            data.kickDetails = {
                // this is different from the room membership in the sync section, which can only be leave
                membership: event.content?.membership, // could be leave or ban
                reason: event.content?.reason,
                sender: event.sender,
            }
        }
    }
    return data;
}

function processTimelineEvent(data, eventEntry, isInitialSync, canMarkUnread, ownUserId) {
    if (eventEntry.eventType === "m.room.message") {
        if (!data.lastMessageTimestamp || eventEntry.timestamp > data.lastMessageTimestamp) {
            data = data.cloneIfNeeded();
            data.lastMessageTimestamp = eventEntry.timestamp;
        }
        if (!isInitialSync && eventEntry.sender !== ownUserId && canMarkUnread) {
            data = data.cloneIfNeeded();
            data.isUnread = true;
        }
    }
    return data;
}

function updateSummary(data, summary) {
    const heroes = summary["m.heroes"];
    const joinCount = summary["m.joined_member_count"];
    const inviteCount = summary["m.invited_member_count"];
    // TODO: we could easily calculate if all members are available here and set hasFetchedMembers?
    // so we can avoid calling /members...
    // we'd need to do a count query in the roomMembers store though ...
    if (heroes && Array.isArray(heroes)) {
        data = data.cloneIfNeeded();
        data.heroes = heroes;
    }
    if (Number.isInteger(inviteCount)) {
        data = data.cloneIfNeeded();
        data.inviteCount = inviteCount;
    }
    if (Number.isInteger(joinCount)) {
        data = data.cloneIfNeeded();
        data.joinCount = joinCount;
    }
    return data;
}

function applyInvite(data, invite) {
    if (data.isDirectMessage !== invite.isDirectMessage) {
        data = data.cloneIfNeeded();
        data.isDirectMessage = invite.isDirectMessage;
        if (invite.isDirectMessage) {
            data.dmUserId = invite.inviter?.userId;
        } else {
            data.dmUserId = null;
        }
    }
    return data;
}

export class SummaryData {
    constructor(copy, roomId) {
        this.roomId = copy ? copy.roomId : roomId;
        this.name = copy ? copy.name : null;
        this.lastMessageTimestamp = copy ? copy.lastMessageTimestamp : null;
        this.isUnread = copy ? copy.isUnread : false;
        this.encryption = copy ? copy.encryption : null;
        this.membership = copy ? copy.membership : null;
        this.inviteCount = copy ? copy.inviteCount : 0;
        this.joinCount = copy ? copy.joinCount : 0;
        this.heroes = copy ? copy.heroes : null;
        this.canonicalAlias = copy ? copy.canonicalAlias : null;
        this.hasFetchedMembers = copy ? copy.hasFetchedMembers : false;
        this.isTrackingMembers = copy ? copy.isTrackingMembers : false;
        this.avatarUrl = copy ? copy.avatarUrl : null;
        this.notificationCount = copy ? copy.notificationCount : 0;
        this.highlightCount = copy ? copy.highlightCount : 0;
        this.tags = copy ? copy.tags : null;
        this.isDirectMessage = copy ? copy.isDirectMessage : false;
        this.dmUserId = copy ? copy.dmUserId : null;
        this.kickDetails = copy ? copy.kickDetails : null;
        this.cloned = copy ? true : false;
    }

    diff(other) {
        const props = Object.getOwnPropertyNames(this);
        return props.reduce((diff, prop) => {
            if (prop !== "cloned") {
                if (this[prop] !== other[prop]) {
                    diff[prop] = this[prop];
                }
            }
            return diff;
        }, {});
    }

    cloneIfNeeded() {
        if (this.cloned) {
            return this;
        } else {
            return new SummaryData(this);
        }
    }

    serialize() {
        const {cloned, ...serializedProps} = this;
        return Object.entries(this).reduce((obj, [key, value]) => {
            if (key !== "cloned" && value !== null) {
                obj[key] = value;
            }
            return obj;
        }, {});
    }

    applyTimelineEntries(timelineEntries, isInitialSync, canMarkUnread, ownUserId) {
        return applyTimelineEntries(this, timelineEntries, isInitialSync, canMarkUnread, ownUserId);
    }

    applySyncResponse(roomResponse, membership, ownUserId) {
        return applySyncResponse(this, roomResponse, membership, ownUserId);
    }

    applyInvite(invite) {
        return applyInvite(this, invite);
    }

    get needsHeroes() {
        return !this.name && !this.canonicalAlias && this.heroes && this.heroes.length > 0;
    }
}

export class RoomSummary {
	constructor(roomId) {
        this._data = null;
        this.applyChanges(new SummaryData(null, roomId));
	}

    get data() {
        return this._data;
    }

    writeClearUnread(txn) {
        const data = new SummaryData(this._data);
        data.isUnread = false;
        data.notificationCount = 0;
        data.highlightCount = 0;
        txn.roomSummary.set(data.serialize());
        return data;
    }

    writeHasFetchedMembers(value, txn) {
        const data = new SummaryData(this._data);
        data.hasFetchedMembers = value;
        txn.roomSummary.set(data.serialize());
        return data;
    }

    writeIsTrackingMembers(value, txn) {
        const data = new SummaryData(this._data);
        data.isTrackingMembers = value;
        txn.roomSummary.set(data.serialize());
        return data;
    }

	writeData(data, txn) {
		if (data !== this._data) {
            txn.roomSummary.set(data.serialize());
            return data;
		}
	}

    /** move summary to archived store when leaving the room */
    removeAndWriteArchive(data, txn) {
        txn.roomSummary.remove(data.roomId);
        if (data !== this._data) {
            txn.archivedRoomSummary.set(data.serialize());
            return data;
        }
    }

    /** delete archived summary when rejoining the room */
    tryRemoveArchive(txn) {
        txn.archivedRoomSummary.remove(this._data.roomId);
    }

    async writeAndApplyData(data, storage) {
        if (data === this._data) {
            return false;
        }
        const txn = await storage.readWriteTxn([
            storage.storeNames.roomSummary,
        ]);
        try {
            txn.roomSummary.set(data.serialize());
        } catch (err) {
            txn.abort();
            throw err;
        }
        await txn.complete();
        this.applyChanges(data);
        return true;
    }

    applyChanges(data) {
        this._data = data;
        // clear cloned flag, so cloneIfNeeded makes a copy and
        // this._data is not modified if any field is changed.
        this._data.cloned = false;
    }

	async load(summary) {
        this.applyChanges(new SummaryData(summary));
	}
}

export function tests() {
    function createMemberEvent(sender, target, membership, reason) {
        return {
            sender,
            state_key: target,
            type: "m.room.member",
            content: { reason, membership }
        };
    }
    const bob = "@bob:hs.tld";
    const alice = "@alice:hs.tld";

    return {
        "serialize doesn't include null fields or cloned": assert => {
            const roomId = "!123:hs.tld";
            const data = new SummaryData(null, roomId);
            const clone = data.cloneIfNeeded();
            const serialized = clone.serialize();
            assert.strictEqual(serialized.cloned, undefined);
            assert.equal(serialized.roomId, roomId);
            const nullCount = Object.values(serialized).reduce((count, value) => count + value === null ? 1 : 0, 0);
            assert.strictEqual(nullCount, 0);
        },
        "ban/kick sets kickDetails from state event": assert => {
            const reason = "Bye!";
            const leaveEvent = createMemberEvent(alice, bob, "ban", reason);
            const data = new SummaryData(null, "!123:hs.tld");
            const newData = data.applySyncResponse({state: {events: [leaveEvent]}}, "leave", bob);
            assert.equal(newData.membership, "leave");
            assert.equal(newData.kickDetails.membership, "ban");
            assert.equal(newData.kickDetails.reason, reason);
            assert.equal(newData.kickDetails.sender, alice);
        },
        "ban/kick sets kickDetails from timeline state event, taking precedence over state": assert => {
            const reason = "Bye!";
            const inviteEvent = createMemberEvent(alice, bob, "invite");
            const leaveEvent = createMemberEvent(alice, bob, "ban", reason);
            const data = new SummaryData(null, "!123:hs.tld");
            const newData = data.applySyncResponse({
                state: { events: [inviteEvent] },
                timeline: {events: [leaveEvent] }
            }, "leave", bob);
            assert.equal(newData.membership, "leave");
            assert.equal(newData.kickDetails.membership, "ban");
            assert.equal(newData.kickDetails.reason, reason);
            assert.equal(newData.kickDetails.sender, alice);
        },
        "leaving without being kicked doesn't produce kickDetails": assert => {
            const leaveEvent = createMemberEvent(bob, bob, "leave");
            const data = new SummaryData(null, "!123:hs.tld");
            const newData = data.applySyncResponse({state: {events: [leaveEvent]}}, "leave", bob);
            assert.equal(newData.membership, "leave");
            assert.equal(newData.kickDetails, null);
        },
        "membership trigger change": function(assert) {
            const summary = new RoomSummary("id");
            let written = false;
            let changes = summary.data.applySyncResponse({}, "join");
            const txn = {roomSummary: {set: () => { written = true; }}};
            changes = summary.writeData(changes, txn);
            assert(changes);
            assert(written);
            assert.equal(changes.membership, "join");
        }
    }
}