const chai = require('chai');
const chaiHttp = require('chai-http');
const express = require('express');
import { expect } from 'chai';
import { SetupApp } from '../../../app';
import { ReferenceDatabase } from '../../reference_model/DBReferenceModel';
import { randomDBAction, RandomDBActionDistribution, DBActionType, applyReferenceDBAction, applyRealDBAction, DBAction } from '../../reference_model/randomGen';
import * as helpers from '../helpers';
import seedrandom from 'seedrandom';
import { AlbumWithRefsWithId, Artist, ArtistWithRefsWithId, DBImportResponse, IDMappings, TagWithRefsWithId, TrackWithRefs, TrackWithRefsWithId } from '../../../../client/src/api/api';
import sampleDB from '../sampleDB';
let stringify = require('json-stringify-deterministic');

let _ = require('lodash');
let tmp = require('tmp');
let fs = require('fs');

async function init() {
    chai.use(chaiHttp);
    const app = express();
    const knex = await helpers.initTestDB();

    SetupApp(app, knex, '');

    var agent = chai.request.agent(app);
    return agent;
}

// Alters a response from a real or mock DB so that they can be deep-compared
// and only non-trivial differences trigger an error.
function normalizeResponse(response: any) {
    let r: any = _.cloneDeep(response);
    if (r && 'id' in r) {
        r.id = '<redacted>';
    }
    return r;
}

// Alters a database export / reference database model so that it can be compared
// to another so that only non-trivial differences trigger an error.
function normalizeDB(oldDb: ReferenceDatabase) {
    let db: ReferenceDatabase = _.cloneDeep(oldDb);


    // Apply a deterministic sorting.
    // TODO: sorting by name is not deterministic.
    for (const userId in db) {
        db[userId].tracks.sort((a: any, b: any) => a.name.localeCompare(b.name))
        db[userId].albums.sort((a: any, b: any) => a.name.localeCompare(b.name))
        db[userId].artists.sort((a: any, b: any) => a.name.localeCompare(b.name))
        db[userId].tags.sort((a: any, b: any) => a.name.localeCompare(b.name))
    }

    // Re-map IDs.
    interface IDMap {
        map: Map<number, number>,
        highestId: number,
    };
    let trackMap: IDMap = { map: new Map<number, number>(), highestId: 0 };
    let albumMap: IDMap = { map: new Map<number, number>(), highestId: 0 };
    let artistMap: IDMap = { map: new Map<number, number>(), highestId: 0 };
    let tagMap: IDMap = { map: new Map<number, number>(), highestId: 0 };
    let remapId = (id: number, map: IDMap) => {
        if (map.map.has(id)) { return map.map.get(id) as number; }
        let newId: number = map.highestId + 1;
        map.map.set(id, newId);
        map.highestId = newId;
        return newId;
    }
    for (const userId in db) {
        // First remap the IDs only, ignoring references
        db[userId].tracks.forEach((x: TrackWithRefsWithId) => { x.id = remapId(x.id, trackMap); });
        db[userId].albums.forEach((x: AlbumWithRefsWithId) => { x.id = remapId(x.id, albumMap); })
        db[userId].artists.forEach((x: ArtistWithRefsWithId) => { x.id = remapId(x.id, artistMap); })
        db[userId].tags.forEach((x: TagWithRefsWithId) => { x.id = remapId(x.id, tagMap); })
    }
    for (const userId in db) {
        // Now remap the references.
        db[userId].tracks.forEach((x: TrackWithRefsWithId) => {
            x.tagIds = x.tagIds.map((id: number) => remapId(id, tagMap));
            x.artistIds = x.artistIds.map((id: number) => remapId(id, artistMap));
            x.albumId = x.albumId ? remapId(x.albumId, albumMap) : null;
        });
        db[userId].albums.forEach((x: AlbumWithRefsWithId) => {
            x.tagIds = x.tagIds.map((id: number) => remapId(id, tagMap));
            x.artistIds = x.artistIds.map((id: number) => remapId(id, artistMap));
            x.trackIds = x.trackIds.map((id: number) => remapId(id, trackMap));
        });
        db[userId].artists.forEach((x: ArtistWithRefsWithId) => {
            x.tagIds = x.tagIds.map((id: number) => remapId(id, tagMap));
            x.albumIds = x.albumIds.map((id: number) => remapId(id, albumMap));
            x.trackIds = x.trackIds.map((id: number) => remapId(id, trackMap));
        });
        db[userId].tags.forEach((x: TagWithRefsWithId) => {
            x.parentId = x.parentId ? remapId(x.parentId, tagMap) : null;
        });
    }

    return db;
}

// Transform all referenced IDs in an action given a mapping.
function transformActionIDs(action: DBAction, mappings: IDMappings, rng: any) {
    let r: DBAction = _.cloneDeep(action);

    let doMap = (id: number, mapping: Record<number, number>) => {
        if (id in mapping) {
            return mapping[id];
        }
        // Number is not in the map. Generate something that will be nonexistent
        // for sure.
        let highest = 0;
        for (const [_, value] of Object.entries(mapping)) {
            highest = Math.max(value, highest);
        }
        let r = highest + 1 + Math.floor(rng() * 100);
        return r;
    }

    switch (r.type) {
        case DBActionType.CreateTrack: {
            let track = r.payload as TrackWithRefsWithId;
            track.tagIds.forEach((id: number) => doMap(id, mappings.tags));
            track.artistIds.forEach((id: number) => doMap(id, mappings.artists));
            track.albumId = track.albumId ? doMap(track.albumId, mappings.albums) : null;
            break;
        }
        case DBActionType.CreateArtist: {
            let artist = r.payload as ArtistWithRefsWithId;
            artist.tagIds.forEach((id: number) => doMap(id, mappings.tags));
            artist.albumIds.forEach((id: number) => doMap(id, mappings.albums));
            artist.trackIds.forEach((id: number) => doMap(id, mappings.tracks));
            break;
        }
        case DBActionType.CreateAlbum: {
            let album = r.payload as AlbumWithRefsWithId;
            album.tagIds.forEach((id: number) => doMap(id, mappings.tags));
            album.artistIds.forEach((id: number) => doMap(id, mappings.artists));
            album.trackIds.forEach((id: number) => doMap(id, mappings.tracks));
            break;
        }
        case DBActionType.CreateTag: {
            let tag = r.payload as TagWithRefsWithId;
            tag.parentId = tag.parentId ? doMap(tag.parentId, mappings.tags) : null;
            break;
        }
        case DBActionType.DeleteTrack:
        case DBActionType.DeleteArtist:
        case DBActionType.DeleteAlbum:
        case DBActionType.DeleteTag:
            {
                let keys = {
                    [DBActionType.DeleteTrack]: 'tracks',
                    [DBActionType.DeleteArtist]: 'artists',
                    [DBActionType.DeleteAlbum]: 'albums',
                    [DBActionType.DeleteTag]: 'tags',
                }
                r.payload = (mappings as any)[keys[r.type]][r.payload];
                break;
            }
    }
    return r;
}


// This test is designed to find corner-cases in the back-end API implementation.
// Operations are performed on the API while also being performed on a simplified
// reference model.
// The database is compared after each operation by exporting it through the export
// endpoint.
// This way, the import, export and resource operations are all thoroughly tested
// in a random way, assuming that the reference model is the "gold standard".
describe('Randomized model-based DB back-end tests', () => {
    it('all succeed', async done => {
        // Get a handle to perform API requests.
        let req = await init();

        // Keep a trace of the actions that have been performed, for debugging purposes.
        let actionTrace: DBAction[] = [];

        // Seed the random number generator so that the test run can be reproduced.
        let seed: string = process.env.TEST_RANDOM_SEED || Math.random().toFixed(5).toString();
        console.log(`Test random seed: '${seed}'`)

        // Keep track of database states.
        let refState: ReferenceDatabase | undefined = undefined;
        let realState: ReferenceDatabase | undefined = undefined;

        // As we perform operations, the real DB and reference model may assign
        // different new IDs to new objects. We need to maintain mappings in order
        // to keep the operations consistent (e.g. when we make references to)
        // existing objects along the way.
        let idMappingsRefToReal: IDMappings | undefined = undefined;

        try {
            // Create a reference DB.
            let refDB: ReferenceDatabase = _.cloneDeep(sampleDB);

            // Prime the real DB
            // First, create a user and log in.
            await helpers.createUser(req, "someone@email.com", "password1A!", 200);
            await helpers.login(req, "someone@email.com", "password1A!", 200);
            // Import the starting DB.
            let importResponse: DBImportResponse = (await helpers.importDB(req, refDB[1])).body;
            idMappingsRefToReal = importResponse;

            // Check that we are starting from an equal situation
            refState = refDB;
            realState = {
                [1]: (await helpers.getExport(req)).body,
            };
            expect(normalizeDB(realState)).to.deep.equal(normalizeDB(refState));

            // Create a random number generator to use throughout the test.
            let rng = seedrandom(seed);

            // This distribution determines the kind of random actions that will
            // be generated.
            let dist: RandomDBActionDistribution = {
                type: new Map([
                    [DBActionType.CreateTrack, 0.0625],
                    [DBActionType.CreateArtist, 0.0625],
                    [DBActionType.CreateAlbum, 0.0625],
                    [DBActionType.CreateTag, 0.0625],
                    [DBActionType.PutTrack, 0.0625],
                    [DBActionType.PutArtist, 0.0625],
                    [DBActionType.PutAlbum, 0.0625],
                    [DBActionType.PutTag, 0.0625],
                    [DBActionType.PatchTrack, 0.0625],
                    [DBActionType.PatchArtist, 0.0625],
                    [DBActionType.PatchAlbum, 0.0625],
                    [DBActionType.PatchTag, 0.0625],
                    [DBActionType.DeleteTrack, 0.0625],
                    [DBActionType.DeleteArtist, 0.0625],
                    [DBActionType.DeleteAlbum, 0.0625],
                    [DBActionType.DeleteTag, 0.0625],
                ]),
                userId: new Map([[1, 1.0]]),
                createTrackParams: {
                    linkAlbum: new Map<boolean | 'nonexistent', number>([[false, 0.45], [true, 0.45], ['nonexistent', 0.1]]),
                    linkTags: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkArtists: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                },
                createAlbumParams: {
                    linkTracks: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkTags: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkArtists: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                },
                createArtistParams: {
                    linkTracks: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkTags: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkAlbums: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                },
                createTagParams: {
                    linkParent: new Map<boolean | 'nonexistent', number>([[false, 0.45], [true, 0.45], ['nonexistent', 0.1]]),

                },
                putTrackParams: {
                    linkAlbum: new Map<boolean | 'nonexistent', number>([[false, 0.45], [true, 0.45], ['nonexistent', 0.1]]),
                    linkTags: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkArtists: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    validId: new Map([[false, 0.3], [true, 0.7]]),
                },
                putAlbumParams: {
                    linkTracks: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkTags: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkArtists: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    validId: new Map([[false, 0.3], [true, 0.7]]),
                },
                putArtistParams: {
                    linkTracks: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkTags: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkAlbums: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    validId: new Map([[false, 0.3], [true, 0.7]]),
                },
                putTagParams: {
                    linkParent: new Map<boolean | 'nonexistent', number>([[false, 0.45], [true, 0.45], ['nonexistent', 0.1]]),
                    validId: new Map([[false, 0.3], [true, 0.7]]),
                },
                patchTrackParams: {
                    linkAlbum: new Map<boolean | 'nonexistent', number>([[false, 0.45], [true, 0.45], ['nonexistent', 0.1]]),
                    linkTags: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkArtists: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    replaceName: new Map([[false, 0.5], [true, 0.5]]),
                    replaceTags: new Map([[false, 0.5], [true, 0.5]]),
                    replaceAlbum: new Map([[false, 0.5], [true, 0.5]]),
                    replaceArtists: new Map([[false, 0.5], [true, 0.5]]),
                    validId: new Map([[false, 0.3], [true, 0.7]]),
                },
                patchAlbumParams: {
                    linkTracks: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkTags: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkArtists: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    replaceName: new Map([[false, 0.5], [true, 0.5]]),
                    replaceTags: new Map([[false, 0.5], [true, 0.5]]),
                    replaceTracks: new Map([[false, 0.5], [true, 0.5]]),
                    replaceArtists: new Map([[false, 0.5], [true, 0.5]]),
                    validId: new Map([[false, 0.3], [true, 0.7]]),
                },
                patchArtistParams: {
                    linkTracks: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkTags: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    linkAlbums: {
                        numValid: new Map([[0, 1.0]]),
                        numInvalid: new Map([[0, 0.9], [1, 0.05], [2, 0.05]]),
                    },
                    replaceName: new Map([[false, 0.5], [true, 0.5]]),
                    replaceTags: new Map([[false, 0.5], [true, 0.5]]),
                    replaceTracks: new Map([[false, 0.5], [true, 0.5]]),
                    replaceAlbums: new Map([[false, 0.5], [true, 0.5]]),
                    validId: new Map([[false, 0.3], [true, 0.7]]),
                },
                patchTagParams: {
                    linkParent: new Map<boolean | 'nonexistent', number>([[false, 0.45], [true, 0.45], ['nonexistent', 0.1]]),
                    replaceName: new Map([[false, 0.5], [true, 0.5]]),
                    replaceParent: new Map([[false, 0.5], [true, 0.5]]),
                    validId: new Map([[false, 0.3], [true, 0.7]]),
                },
                deleteTrackParams: {
                    validId: new Map([[false, 0.2], [true, 0.8]])
                },
                deleteArtistParams: {
                    validId: new Map([[false, 0.2], [true, 0.8]])
                },
                deleteAlbumParams: {
                    validId: new Map([[false, 0.2], [true, 0.8]])
                },
                deleteTagParams: {
                    validId: new Map([[false, 0.2], [true, 0.8]])
                },
            }

            // Loop to generate and execute a bunch of random actions.
            for (let i = 0; i < 100; i++) {

                // Generate an action (based on the reference DB)
                let refAction = randomDBAction(
                    refDB,
                    rng,
                    dist
                );
                actionTrace.push(refAction);
                console.log("Testing action: ", refAction);

                // Transform any referenced IDs using the ID mapping
                let realAction = transformActionIDs(refAction, idMappingsRefToReal, rng);

                // Apply the action to the real and reference DB.
                let { response: refResponse, status: refStatus } = applyReferenceDBAction(refAction, refDB);
                let { response: realResponse, status: realStatus } = await applyRealDBAction(realAction, req);

                // If this was an object creation action, we need to update the mappings.
                if (refStatus === 200 && realStatus === 200) {
                    switch (refAction.type) {
                        case DBActionType.CreateTrack: { idMappingsRefToReal.tracks[refResponse.id] = realResponse.id; break; }
                        case DBActionType.CreateArtist: { idMappingsRefToReal.artists[refResponse.id] = realResponse.id; break; }
                        case DBActionType.CreateAlbum: { idMappingsRefToReal.albums[refResponse.id] = realResponse.id; break; }
                        case DBActionType.CreateTag: { idMappingsRefToReal.tags[refResponse.id] = realResponse.id; break; }
                        default: { break; }
                    }
                }

                // Compare the response and status.
                expect(realStatus).to.equal(refStatus);
                expect(normalizeResponse(realResponse)).to.deep.equal(normalizeResponse(refResponse));

                // Compare the database state after the action.
                let newRefState = _.cloneDeep(refDB);
                let newRealState = {
                    [1]: (await helpers.getExport(req)).body,
                };
                expect(normalizeDB(newRealState)).to.deep.equal(normalizeDB(newRefState));
                realState = newRealState;
                refState = newRefState;
            }
        } catch (e) {
            // When catching a comparison error, add and dump various states to files for debugging.
            e.actionTrace = actionTrace;
            e.startingDB = normalizeDB(sampleDB);
            e.lastRefDB = refState;
            e.lastRealDB = realState;
            e.testSeed = seed;
            e.idMappingsRefToReal = idMappingsRefToReal;
            if (e.actual && e.expected) {
                let basename = tmp.tmpNameSync();
                e.actualDump = basename + "_actual";
                e.expectedDump = basename + "_expected";
                e.actionTraceDump = basename + "_actiontrace";
                e.startingDBDump = basename + "_startingDB";
                e.lastRefDBDump = basename + "_lastRefDB";
                e.lastRealDBDump = basename + "_lastRealDB";
                e.idMappingsRefToRealDump = basename + "_idMappings";
                fs.writeFileSync(e.actualDump, stringify(e.actual, { space: '  ' }));
                fs.writeFileSync(e.expectedDump, stringify(e.expected, { space: '  ' }));
                fs.writeFileSync(e.actionTraceDump, stringify(e.actionTrace, { space: '  ' }));
                fs.writeFileSync(e.startingDBDump, stringify(e.startingDB, { space: '  ' }));
                fs.writeFileSync(e.lastRefDBDump, stringify(e.lastRefDB, { space: '  ' }));
                fs.writeFileSync(e.lastRealDBDump, stringify(e.lastRealDB, { space: '  ' }));
                fs.writeFileSync(e.idMappingsRefToRealDump, stringify(e.idMappingsRefToReal, { space: '  ' }));

                console.log(
                    "A comparison error occurred. Wrote compared values to temporary files for debugging:\n"
                    + `  Actual value: ${e.actualDump}\n`
                    + `  Expected value: ${e.actualDump}\n`
                    + `  DB action trace: ${e.actionTraceDump}\n`
                    + `  Starting DB: ${e.startingDBDump}\n`
                    + `  Reference DB before last action: ${e.lastRefDBDump}\n`
                    + `  Real DB before last action: ${e.lastRealDBDump}\n`
                    + `  ID Mappings from ref to real DB: ${e.idMappingsRefToRealDump}\n`
                    + `  TEST_RANDOM_SEED: ${seed}`
                );
            }
            throw e;
        } finally {
            req.close();
            done();
        }
    });
});