/**
 * Copyright (c) 2018 mol* contributors, licensed under MIT, See LICENSE file for more info.
 *
 * Taken/adapted from DensityServer (https://github.com/dsehnal/DensityServer)
 *
 * @author David Sehnal <david.sehnal@gmail.com>
 */

import * as express from 'express'

import * as Api from './api'

import * as Data from './query/data-model'
import * as Coords from './algebra/coordinate'
import Docs from './documentation'
import ServerConfig from '../server-config'
import { ConsoleLogger } from 'mol-util/console-logger'
import { State } from './state'

export default function init(app: express.Express) {
    function makePath(p: string) {
        return ServerConfig.apiPrefix + '/' + p;
    }

    // Header
    app.get(makePath(':source/:id/?$'), (req, res) => getHeader(req, res));
    // Box /:src/:id/box/:a1,:a2,:a3/:b1,:b2,:b3?text=0|1&space=cartesian|fractional
    app.get(makePath(':source/:id/box/:a1,:a2,:a3/:b1,:b2,:b3/?'), (req, res) => queryBox(req, res, getQueryParams(req, false)));
    // Cell /:src/:id/cell/?text=0|1&space=cartesian|fractional
    app.get(makePath(':source/:id/cell/?'), (req, res) => queryBox(req, res, getQueryParams(req, true)));

    app.get('*', (req, res) => {
        res.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8' });
        res.end(Docs);
    });
}

function mapFile(type: string, id: string) {
    return ServerConfig.mapFile(type || '', id || '');
}

function wrapResponse(fn: string, res: express.Response) {
    const w = {
        do404(this: any) {
            if (!this.headerWritten) {
                res.writeHead(404);
                this.headerWritten = true;
            }
            this.end();
        },
        writeHeader(this: any, binary: boolean) {
            if (this.headerWritten) return;
            res.writeHead(200, {
                'Content-Type': binary ? 'application/octet-stream' : 'text/plain; charset=utf-8',
                'Access-Control-Allow-Origin': '*',
                'Access-Control-Allow-Headers': 'X-Requested-With',
                'Content-Disposition': `inline; filename="${fn}"`
            });
            this.headerWritten = true;
        },
        writeBinary(this: any, data: Uint8Array) {
            if (!this.headerWritten) this.writeHeader(true);
            return res.write(Buffer.from(data.buffer));
        },
        writeString(this: any, data: string) {
            if (!this.headerWritten) this.writeHeader(false);
            return res.write(data);
        },
        end(this: any) {
            if (this.ended) return;
            res.end();
            this.ended = true;
        },
        ended: false,
        headerWritten: false
    };

    return w;
}

function getSourceInfo(req: express.Request) {
    return {
        filename: mapFile(req.params.source, req.params.id),
        id: `${req.params.source}/${req.params.id}`
    };
}

function validateSourndAndId(req: express.Request, res: express.Response) {
    if (!req.params.source || req.params.source.length > 32 || !req.params.id || req.params.source.id > 32) {
        res.writeHead(404);
        res.end();
        ConsoleLogger.error(`Query Box`, 'Invalid source and/or id');
        return true;
    }
    return false;
}

async function getHeader(req: express.Request, res: express.Response) {
    if (validateSourndAndId(req, res)) {
        return;
    }

    let headerWritten = false;

    try {
        const { filename, id } = getSourceInfo(req);
        const header = await Api.getHeaderJson(filename, id);
        if (!header) {
            res.writeHead(404);
            return;
        }
        res.writeHead(200, {
            'Content-Type': 'application/json; charset=utf-8',
            'Access-Control-Allow-Origin': '*',
            'Access-Control-Allow-Headers': 'X-Requested-With'
        });
        headerWritten = true;
        res.write(header);
    } catch (e) {
        ConsoleLogger.error(`Header ${req.params.source}/${req.params.id}`, e);
        if (!headerWritten) {
            res.writeHead(404);
        }
    } finally {
        res.end();
    }
}

function getQueryParams(req: express.Request, isCell: boolean): Data.QueryParams {
    const a = [+req.params.a1, +req.params.a2, +req.params.a3];
    const b = [+req.params.b1, +req.params.b2, +req.params.b3];

    const detail = Math.min(Math.max(0, (+req.query.detail) | 0), ServerConfig.limits.maxOutputSizeInVoxelCountByPrecisionLevel.length - 1)
    const isCartesian = (req.query.space || '').toLowerCase() !== 'fractional';

    const box: Data.QueryParamsBox = isCell
        ? { kind: 'Cell' }
        : (isCartesian
            ? { kind: 'Cartesian', a: Coords.cartesian(a[0], a[1], a[2]), b: Coords.cartesian(b[0], b[1], b[2]) }
            : { kind: 'Fractional', a: Coords.fractional(a[0], a[1], a[2]), b: Coords.fractional(b[0], b[1], b[2]) });

    const asBinary = (req.query.encoding || '').toLowerCase() !== 'cif';
    const sourceFilename = mapFile(req.params.source, req.params.id)!;

    return {
        sourceFilename,
        sourceId: `${req.params.source}/${req.params.id}`,
        asBinary,
        box,
        detail
    };
}

async function queryBox(req: express.Request, res: express.Response, params: Data.QueryParams) {
    if (validateSourndAndId(req, res)) {
        return;
    }

    const outputFilename = Api.getOutputFilename(req.params.source, req.params.id, params);
    const response = wrapResponse(outputFilename, res);

    try {
        if (!params.sourceFilename) {
            response.do404();
            return;
        }

        let ok = await Api.queryBox(params, () => response);
        if (!ok) {
            response.do404();
            return;
        }
    } catch (e) {
        ConsoleLogger.error(`Query Box ${JSON.stringify(req.params || {})} | ${JSON.stringify(req.query || {})}`, e);
        response.do404();
    } finally {
        response.end();
        queryDone();
    }
}

function queryDone() {
    if (State.shutdownOnZeroPending) {
        process.exit(0);
    }
}