/**
 * Building data access
 *
 */
import { ITask } from 'pg-promise';

import db from '../../db';
import { tileCache } from '../../tiles/rendererDefinition';
import { BoundingBox } from '../../tiles/types';

// data type note: PostgreSQL bigint (64-bit) is handled as string in JavaScript, because of
// JavaScript numerics are 64-bit double, giving only partial coverage.

const TransactionMode = db.$config.pgp.txMode.TransactionMode;
const isolationLevel = db.$config.pgp.txMode.isolationLevel;

// Create a transaction mode (serializable, read-write):
const serializable = new TransactionMode({
    tiLevel: isolationLevel.serializable,
    readOnly: false
});

async function getLatestRevisionId() {
    try {
        const data = await db.oneOrNone(
            `SELECT MAX(log_id) from logs`
        );
        return data == undefined ? undefined : data.max;
    } catch(err) {
        console.error(err);
        return undefined;
    }
}


async function queryBuildingsAtPoint(lng: number, lat: number) {
    try {
        return await db.manyOrNone(
            `SELECT b.*
            FROM buildings as b, geometries as g
            WHERE
                b.geometry_id = g.geometry_id
            AND
                ST_Intersects(
                    ST_Transform(
                        ST_SetSRID(ST_Point($1, $2), 4326),
                        3857
                    ),
                    geometry_geom
                )
            `,
            [lng, lat]
        );
    } catch(error) {
        console.error(error);
        return undefined;
    }
}

async function queryBuildingsByReference(key: string, ref: string) {
    try {
        if (key === 'toid') {
            return await db.manyOrNone(
                `SELECT
                    *
                FROM
                    buildings
                WHERE
                    ref_toid = $1
                `,
                [ref]
            );
        } else if (key === 'uprn') {
            return await db.manyOrNone(
                `SELECT
                    b.*
                FROM
                    buildings as b, building_properties as p
                WHERE
                    b.building_id = p.building_id
                AND
                    p.uprn = $1
                `,
                [ref]
            );
        } else {
            return { error: 'Key must be UPRN or TOID' };
        }
    } catch(err) {
        console.error(err);
        return undefined;
    }
}

async function getBuildingById(id: number) {
    try {
        const building = await db.one(
            'SELECT * FROM buildings WHERE building_id = $1',
            [id]
        );

        building.edit_history = await getBuildingEditHistory(id);

        return building;
    } catch(error) {
        console.error(error);
        return undefined;
    }
}

async function getBuildingEditHistory(id: number) {
    try {
        return await db.manyOrNone(
            `SELECT log_id as revision_id, forward_patch, reverse_patch, date_trunc('minute', log_timestamp), username
            FROM logs, users
            WHERE building_id = $1 AND logs.user_id = users.user_id
            ORDER BY log_timestamp DESC`,
            [id]
        );
    } catch(error) {
        console.error(error);
        return [];
    }
}

async function getBuildingLikeById(buildingId: number, userId: string) {
    try {
        const res = await db.oneOrNone(
            'SELECT true as like FROM building_user_likes WHERE building_id = $1 and user_id = $2 LIMIT 1',
            [buildingId, userId]
        );
        return res && res.like;
    } catch(error) {
        console.error(error);
        return undefined;
    }
}

async function getBuildingUPRNsById(id: number) {
    try {
        return await db.any(
            'SELECT uprn, parent_uprn FROM building_properties WHERE building_id = $1',
            [id]
        );
    } catch(error) {
        console.error(error);
        return undefined;
    }
}

async function saveBuilding(buildingId: number, building: any, userId: string) { // TODO add proper building type
    try {
        return await updateBuildingData(buildingId, userId, async () => {
            // remove read-only fields from consideration
            delete building.building_id;
            delete building.revision_id;
            delete building.geometry_id;

            // return whitelisted fields to update
            return pickAttributesToUpdate(building, BUILDING_FIELD_WHITELIST);
        });
    } catch(error) {
        console.error(error);
        return { error: error };
    }
}

async function likeBuilding(buildingId: number, userId: string) {
    try {
        return await updateBuildingData(
            buildingId,
            userId,
            async (t) => {
                // return total like count after update
                return getBuildingLikeCount(buildingId, t);
            },
            async (t) => {
                // insert building-user like
                await t.none(
                    'INSERT INTO building_user_likes ( building_id, user_id ) VALUES ($1, $2);',
                    [buildingId, userId]
                );
            },
        );
    } catch (error) {
        console.error(error);
        if (error.detail && error.detail.includes('already exists')) {
            // 'already exists' is thrown if user already liked it
            return { error: 'It looks like you already like that building!' };
        } else {
            return undefined;
        }
    }
}

async function unlikeBuilding(buildingId: number, userId: string) {
    try {
        return await updateBuildingData(
            buildingId,
            userId,
            async (t) => {
                // return total like count after update
                return getBuildingLikeCount(buildingId, t);
            },
            async (t) => {
                // remove building-user like
                const result = await t.result(
                    'DELETE FROM building_user_likes WHERE building_id = $1 AND user_id = $2;',
                    [buildingId, userId]
                );

                if (result.rowCount === 0) {
                    throw new Error('No change');
                }
            },
        );
    } catch(error) {
        console.error(error);
        if (error.message === 'No change') {
            // 'No change' is thrown if user doesn't like this building
            return { error: 'It looks like you have already revoked your like for that building!' };
        } else {
            return undefined;
        }
    }
}

// === Utility functions ===

function pickAttributesToUpdate(obj: any, fieldWhitelist: Set<string>) {
    const subObject = {};
    for (let [key, value] of Object.entries(obj)) {
        if(fieldWhitelist.has(key)) {
            subObject[key] = value;
        }
    }
    return subObject;
}

/**
 * 
 * @param buildingId ID of the building to count likes for
 * @param t The database context inside which the count should happen
 */
function getBuildingLikeCount(buildingId: number, t: ITask<unknown>) {
    return t.one(
        'SELECT count(*) as likes_total FROM building_user_likes WHERE building_id = $1;',
        [buildingId]
    );
}

/**
 * Carry out an update of the buildings data. Allows for running any custom database operations before the main update.
 * All db hooks get passed a transaction.
 * @param buildingId The ID of the building to update
 * @param userId The ID of the user updating the data
 * @param getUpdateValue Function returning the set of attribute to update for the building
 * @param preUpdateDbAction Any db operations to carry out before updating the buildings table (mostly intended for updating the user likes table)
 */
async function updateBuildingData(
    buildingId: number,
    userId: string,
    getUpdateValue: (t: ITask<any>) => Promise<object>,
    preUpdateDbAction?: (t: ITask<any>) => Promise<void>,
) {
    return await db.tx({mode: serializable}, async t => {
        if (preUpdateDbAction != undefined) {
            await preUpdateDbAction(t);
        }

        const update = await getUpdateValue(t);

        const oldBuilding = await t.one(
            'SELECT * FROM buildings WHERE building_id = $1 FOR UPDATE;',
            [buildingId]
        );

        console.log(update);
        const patches = compare(oldBuilding, update);
        console.log('Patching', buildingId, patches);
        const [forward, reverse] = patches;
        if (Object.keys(forward).length === 0) {
            throw 'No change provided';
        }

        const revision = await t.one(
            `INSERT INTO logs (
                        forward_patch, reverse_patch, building_id, user_id
                    ) VALUES (
                        $1:json, $2:json, $3, $4
                    ) RETURNING log_id
                    `,
            [forward, reverse, buildingId, userId]
        );

        const sets = db.$config.pgp.helpers.sets(forward);
        console.log('Setting', buildingId, sets);

        const data = await t.one(
            `UPDATE
                    buildings
                SET
                    revision_id = $1,
                    $2:raw
                WHERE
                    building_id = $3
                RETURNING
                    *
                `,
            [revision.log_id, sets, buildingId]
        );

        expireBuildingTileCache(buildingId);

        return data;
    });
}

function privateQueryBuildingBBOX(buildingId: number){
    return db.one(
        `SELECT
            ST_XMin(envelope) as xmin,
            ST_YMin(envelope) as ymin,
            ST_XMax(envelope) as xmax,
            ST_YMax(envelope) as ymax
        FROM (
            SELECT
                ST_Envelope(g.geometry_geom) as envelope
            FROM buildings as b, geometries as g
            WHERE
                b.geometry_id = g.geometry_id
            AND
                b.building_id = $1
        ) as envelope`,
        [buildingId]
    );
}

async function expireBuildingTileCache(buildingId: number) {
    const bbox = await privateQueryBuildingBBOX(buildingId);
    const buildingBbox: BoundingBox = [bbox.xmax, bbox.ymax, bbox.xmin, bbox.ymin];
    tileCache.removeAllAtBbox(buildingBbox);
}

const BUILDING_FIELD_WHITELIST = new Set([
    'ref_osm_id',
    // 'location_name',
    'location_number',
    // 'location_street',
    // 'location_line_two',
    'location_town',
    'location_postcode',
    'location_latitude',
    'location_longitude',
    'date_year',
    'date_lower',
    'date_upper',
    'date_source',
    'date_source_detail',
    'date_link',
    'facade_year',
    'facade_upper',
    'facade_lower',
    'facade_source',
    'facade_source_detail',
    'size_storeys_attic',
    'size_storeys_core',
    'size_storeys_basement',
    'size_height_apex',
    'size_floor_area_ground',
    'size_floor_area_total',
    'size_width_frontage',
    'planning_portal_link',
    'planning_in_conservation_area',
    'planning_conservation_area_name',
    'planning_in_list',
    'planning_list_id',
    'planning_list_cat',
    'planning_list_grade',
    'planning_heritage_at_risk_id',
    'planning_world_list_id',
    'planning_in_glher',
    'planning_glher_url',
    'planning_in_apa',
    'planning_apa_name',
    'planning_apa_tier',
    'planning_in_local_list',
    'planning_local_list_url',
    'planning_in_historic_area_assessment',
    'planning_historic_area_assessment_url',
    'sust_breeam_rating',
    'sust_dec',
    // 'sust_aggregate_estimate_epc',
    'sust_retrofit_date',
    // 'sust_life_expectancy',
    'building_attachment_form',
    'date_change_building_use',
]);

/**
 * Compare old and new data objects, generate shallow merge patch of changed fields
 * - forward patch is object with {keys: new_values}
 * - reverse patch is object with {keys: old_values}
 *
 * @param {object} oldObj
 * @param {object} newObj
 * @param {Set} whitelist
 * @returns {[object, object]}
 */
function compare(oldObj: object, newObj: object): [object, object] {
    const reverse = {};
    const forward = {};
    for (const [key, value] of Object.entries(newObj)) {
        if (oldObj[key] != value) {
            reverse[key] = oldObj[key];
            forward[key] = value;
        }
    }
    return [forward, reverse];
}

export {
    queryBuildingsAtPoint,
    queryBuildingsByReference,
    getBuildingById,
    getBuildingLikeById,
    getBuildingEditHistory,
    getBuildingUPRNsById,
    saveBuilding,
    likeBuilding,
    unlikeBuilding,
    getLatestRevisionId
};