const sql = require('./sql');
const sqlInit = require('./sql_init');
const eventService = require('./events');
const repository = require('./repository');
const protectedSessionService = require('./protected_session');
const utils = require('./utils');
const hoistedNoteService = require('./hoisted_note');
const stringSimilarity = require('string-similarity');

/** @type {Object.<String, Note>} */
let notes;
/** @type {Object.<String, Branch>} */
let branches
/** @type {Object.<String, Attribute>} */
let attributes;

/** @type {Object.<String, Attribute[]>} */
let noteAttributeCache = {};

let childParentToBranch = {};

class Note {
    constructor(row) {
        /** @param {string} */
        this.noteId = row.noteId;
        /** @param {string} */
        this.title = row.title;
        /** @param {boolean} */
        this.isProtected = !!row.isProtected;
        /** @param {Note[]} */
        this.parents = [];
        /** @param {Attribute[]} */
        this.ownedAttributes = [];
    }

    /** @return {Attribute[]} */
    get attributes() {
        if (this.noteId in noteAttributeCache) {
            const attrArrs = [
                this.ownedAttributes
            ];

            for (const templateAttr of this.ownedAttributes.filter(oa => oa.type === 'relation' && oa.name === 'template')) {
                const templateNote = notes[templateAttr.value];

                if (templateNote) {
                    attrArrs.push(templateNote.attributes);
                }
            }

            if (this.noteId !== 'root') {
                for (const parentNote of this.parents) {
                    attrArrs.push(parentNote.inheritableAttributes);
                }
            }

            noteAttributeCache[this.noteId] = attrArrs.flat();
        }

        return noteAttributeCache[this.noteId];
    }

    /** @return {Attribute[]} */
    get inheritableAttributes() {
        return this.attributes.filter(attr => attr.isInheritable);
    }

    hasAttribute(type, name) {
        return this.attributes.find(attr => attr.type === type && attr.name === name);
    }

    get isArchived() {
        return this.hasAttribute('label', 'archived');
    }
}

class Branch {
    constructor(row) {
        /** @param {string} */
        this.branchId = row.branchId;
        /** @param {string} */
        this.noteId = row.noteId;
        /** @param {string} */
        this.parentNoteId = row.parentNoteId;
        /** @param {string} */
        this.prefix = row.prefix;
    }

    /** @return {Note} */
    get parentNote() {
        return notes[this.parentNoteId];
    }
}

class Attribute {
    constructor(row) {
        /** @param {string} */
        this.attributeId = row.attributeId;
        /** @param {string} */
        this.noteId = row.noteId;
        /** @param {string} */
        this.type = row.type;
        /** @param {string} */
        this.name = row.name;
        /** @param {string} */
        this.value = row.value;
        /** @param {boolean} */
        this.isInheritable = row.isInheritable;
    }
}

class FulltextReference {
    /**
     * @param type - attributeName, attributeValue, title
     * @param id - attributeId, noteId
     */
    constructor(type, id) {
        this.type = type;
        this.id = id;
    }
}

/** @type {Object.<String, FulltextReference>} */
let fulltext = {};

/** @type {Object.<String, AttributeMeta>} */
let attributeMetas = {};

class AttributeMeta {
    constructor(attribute) {
        this.type = attribute.type;
        this.name = attribute.name;
        this.isInheritable = attribute.isInheritable;
        this.attributeIds = new Set(attribute.attributeId);
    }

    addAttribute(attribute) {
        this.attributeIds.add(attribute.attributeId);
        this.isInheritable = this.isInheritable || attribute.isInheritable;
    }

    updateAttribute(attribute) {
        if (attribute.isDeleted) {
            this.attributeIds.delete(attribute.attributeId);
        }
        else {
            this.attributeIds.add(attribute.attributeId);
        }

        this.isInheritable = !!this.attributeIds.find(attributeId => attributes[attributeId].isInheritable);
    }
}

function addToAttributeMeta(attribute) {
    const key = `${attribute.type}-${attribute.name}`;

    if (!(key in attributeMetas)) {
        attributeMetas[key] = new AttributeMeta(attribute);
    }
    else {
        attributeMetas[key].addAttribute(attribute);
    }
}

let loaded = false;
let loadedPromiseResolve;
/** Is resolved after the initial load */
let loadedPromise = new Promise(res => loadedPromiseResolve = res);

let noteTitles = {};
let protectedNoteTitles = {};
let noteIds;
const childToParent = {};
let archived = {};

// key is 'childNoteId-parentNoteId' as a replacement for branchId which we don't use here
let prefixes = {};

async function getMappedRows(query, cb) {
    const map = {};
    const results = await sql.getRows(query, []);

    for (const row of results) {
        const keys = Object.keys(row);

        map[row[keys[0]]] = cb(row);
    }

    return map;
}

async function load() {
    notes = await getMappedRows(`SELECT noteId, title, isProtected FROM notes WHERE isDeleted = 0`,
        row => new Note(row));

    for (const note of notes) {
        fulltext[note.title] = fulltext[note.title] || [];
        fulltext[note.title].push(new FulltextReference('note', note.noteId));
    }

    branches = await getMappedRows(`SELECT branchId, noteId, parentNoteId, prefix FROM branches WHERE isDeleted = 0`,
        row => new Branch(row));

    attributes = await getMappedRows(`SELECT attributeId, noteId, type, name, value, isInheritable FROM attributes WHERE isDeleted = 0`,
        row => new Attribute(row));

    for (const attr of attributes) {
        addToAttributeMeta(attributes);

        fulltext[attr.name] = fulltext[attr.name] || [];
        fulltext[attr.name].push(new FulltextReference('aName', attr.attributeId));

        fulltext[attr.value] = fulltext[attr.value] || [];
        fulltext[attr.value].push(new FulltextReference('aVal', attr.attributeId));
    }

    for (const branch of branches) {
        const childNote = notes[branch.noteId];

        if (!childNote) {
            console.log(`Cannot find child note ${branch.noteId} of a branch ${branch.branchId}`);
            continue;
        }

        childNote.parents.push(branch.parentNote);
        childParentToBranch[`${branch.noteId}-${branch.parentNoteId}`] = branch;
    }

    if (protectedSessionService.isProtectedSessionAvailable()) {
        await decryptProtectedNotes();
    }

    loaded = true;
    loadedPromiseResolve();
}

async function decryptProtectedNotes() {
    for (const note of notes) {
        if (note.isProtected) {
            note.title = protectedSessionService.decryptString(note.title);
        }
    }
}

function highlightResults(results, allTokens) {
    // we remove < signs because they can cause trouble in matching and overwriting existing highlighted chunks
    // which would make the resulting HTML string invalid.
    // { and } are used for marking <b> and </b> tag (to avoid matches on single 'b' character)
    allTokens = allTokens.map(token => token.replace('/[<\{\}]/g', ''));

    // sort by the longest so we first highlight longest matches
    allTokens.sort((a, b) => a.length > b.length ? -1 : 1);

    for (const result of results) {
        result.highlightedTitle = result.pathTitle;
    }

    for (const token of allTokens) {
        const tokenRegex = new RegExp("(" + utils.escapeRegExp(token) + ")", "gi");

        for (const result of results) {
            result.highlightedTitle = result.highlightedTitle.replace(tokenRegex, "{$1}");
        }
    }

    for (const result of results) {
        result.highlightedTitle = result.highlightedTitle
            .replace(/{/g, "<b>")
            .replace(/}/g, "</b>");
    }
}

async function findNotes(query) {
    if (!noteTitles || !query.length) {
        return [];
    }

    const allTokens = query
        .trim() // necessary because even with .split() trailing spaces are tokens which causes havoc
        .toLowerCase()
        .split(/[ -]/)
        .filter(token => token !== '/'); // '/' is used as separator

    const tokens = allTokens.slice();
    let results = [];

    for (const noteId in notes) {
        const note = notes[noteId];

        // autocomplete should be able to find notes by their noteIds as well (only leafs)
        if (noteId === query) {
            search(noteId, [], [], results);
            continue;
        }

        // for leaf note it doesn't matter if "archived" label is inheritable or not
        if (note.isArchived) {
            continue;
        }

        for (const parentNote of note.parents) {
            const title = getNoteTitle(note, parentNote).toLowerCase();
            const foundTokens = [];

            for (const token of tokens) {
                if (title.includes(token)) {
                    foundTokens.push(token);
                }
            }

            if (foundTokens.length > 0) {
                const remainingTokens = tokens.filter(token => !foundTokens.includes(token));

                search(parentNote, remainingTokens, [noteId], results);
            }
        }
    }

    if (hoistedNoteService.getHoistedNoteId() !== 'root') {
        results = results.filter(res => res.pathArray.includes(hoistedNoteService.getHoistedNoteId()));
    }

    // sort results by depth of the note. This is based on the assumption that more important results
    // are closer to the note root.
    results.sort((a, b) => {
        if (a.pathArray.length === b.pathArray.length) {
            return a.title < b.title ? -1 : 1;
        }

        return a.pathArray.length < b.pathArray.length ? -1 : 1;
    });

    const apiResults = results.slice(0, 200).map(res => {
        const notePath = res.pathArray.join('/');

        return {
            noteId: res.noteId,
            branchId: res.branchId,
            path: notePath,
            pathTitle: res.titleArray.join(' / '),
            noteTitle: getNoteTitleFromPath(notePath)
        };
    });

    highlightResults(apiResults, allTokens);

    return apiResults;
}

function getBranch(childNoteId, parentNoteId) {
    return childParentToBranch[`${childNoteId}-${parentNoteId}`];
}

function search(note, tokens, path, results) {
    if (tokens.length === 0) {
        const retPath = getSomePath(note, path);

        if (retPath) {
            const thisNoteId = retPath[retPath.length - 1];
            const thisParentNoteId = retPath[retPath.length - 2];

            results.push({
                noteId: thisNoteId,
                branchId: getBranch(thisNoteId, thisParentNoteId),
                pathArray: retPath,
                titleArray: getNoteTitleArrayForPath(retPath)
            });
        }

        return;
    }

    if (!note.parents.length === 0 || noteId === 'root') {
        return;
    }

    for (const parentNote of note.parents) {
        const title = getNoteTitle(note, parentNote).toLowerCase();
        const foundTokens = [];

        for (const token of tokens) {
            if (title.includes(token)) {
                foundTokens.push(token);
            }
        }

        if (foundTokens.length > 0) {
            const remainingTokens = tokens.filter(token => !foundTokens.includes(token));

            search(parentNote, remainingTokens, path.concat([noteId]), results);
        }
        else {
            search(parentNote, tokens, path.concat([noteId]), results);
        }
    }
}

function isNotePathArchived(notePath) {
    const noteId = notePath[notePath.length - 1];

    if (archived[noteId] !== undefined) {
        return true;
    }

    for (let i = 0; i < notePath.length - 1; i++) {
        // this is going through parents so archived must be inheritable
        if (archived[notePath[i]] === 1) {
            return true;
        }
    }

    return false;
}

/**
 * This assumes that note is available. "archived" note means that there isn't a single non-archived note-path
 * leading to this note.
 *
 * @param noteId
 */
function isArchived(noteId) {
    const notePath = getSomePath(noteId);

    return isNotePathArchived(notePath);
}

/**
 * @param {string} noteId
 * @param {string} ancestorNoteId
 * @return {boolean} - true if given noteId has ancestorNoteId in any of its paths (even archived)
 */
function isInAncestor(noteId, ancestorNoteId) {
    if (ancestorNoteId === 'root' || ancestorNoteId === noteId) {
        return true;
    }

    const note = notes[noteId];

    for (const parentNote of notes.parents) {
        if (isInAncestor(parentNote.noteId, ancestorNoteId)) {
            return true;
        }
    }

    return false;
}

function getNoteTitleFromPath(notePath) {
    const pathArr = notePath.split("/");

    if (pathArr.length === 1) {
        return getNoteTitle(pathArr[0], 'root');
    }
    else {
        return getNoteTitle(pathArr[pathArr.length - 1], pathArr[pathArr.length - 2]);
    }
}

function getNoteTitle(childNote, parentNote) {
    let title;

    if (childNote.isProtected) {
        title = protectedSessionService.isProtectedSessionAvailable() ? childNote.title : '[protected]';
    }
    else {
        title = childNote.title;
    }

    const branch = getBranch(childNote.noteId, parentNote.noteId);

    return (branch.prefix ? (branch.prefix + ' - ') : '') + title;
}

function getNoteTitleArrayForPath(path) {
    const titles = [];

    if (path[0] === hoistedNoteService.getHoistedNoteId() && path.length === 1) {
        return [ getNoteTitle(hoistedNoteService.getHoistedNoteId()) ];
    }

    let parentNoteId = 'root';
    let hoistedNotePassed = false;

    for (const noteId of path) {
        // start collecting path segment titles only after hoisted note
        if (hoistedNotePassed) {
            const title = getNoteTitle(noteId, parentNoteId);

            titles.push(title);
        }

        if (noteId === hoistedNoteService.getHoistedNoteId()) {
            hoistedNotePassed = true;
        }

        parentNoteId = noteId;
    }

    return titles;
}

function getNoteTitleForPath(path) {
    const titles = getNoteTitleArrayForPath(path);

    return titles.join(' / ');
}

/**
 * Returns notePath for noteId from cache. Note hoisting is respected.
 * Archived notes are also returned, but non-archived paths are preferred if available
 * - this means that archived paths is returned only if there's no non-archived path
 * - you can check whether returned path is archived using isArchived()
 */
function getSomePath(noteId, path = []) {
    if (noteId === 'root') {
        path.push(noteId);
        path.reverse();

        if (!path.includes(hoistedNoteService.getHoistedNoteId())) {
            return false;
        }

        return path;
    }

    const parents = childToParent[noteId];
    if (!parents || parents.length === 0) {
        return false;
    }

    for (const parentNoteId of parents) {
        const retPath = getSomePath(parentNoteId, path.concat([noteId]));

        if (retPath) {
            return retPath;
        }
    }

    return false;
}

function getNotePath(noteId) {
    const retPath = getSomePath(noteId);

    if (retPath) {
        const noteTitle = getNoteTitleForPath(retPath);
        const parentNoteId = childToParent[noteId][0];

        return {
            noteId: noteId,
            branchId: childParentToBranchId[`${noteId}-${parentNoteId}`],
            title: noteTitle,
            notePath: retPath,
            path: retPath.join('/')
        };
    }
}

function evaluateSimilarity(text1, text2, noteId, results) {
    let coeff = stringSimilarity.compareTwoStrings(text1, text2);

    if (coeff > 0.4) {
        const notePath = getSomePath(noteId);

        // this takes care of note hoisting
        if (!notePath) {
            return;
        }

        if (isNotePathArchived(notePath)) {
            coeff -= 0.2; // archived penalization
        }

        results.push({coeff, notePath, noteId});
    }
}

/**
 * Point of this is to break up long running sync process to avoid blocking
 * see https://snyk.io/blog/nodejs-how-even-quick-async-functions-can-block-the-event-loop-starve-io/
 */
function setImmediatePromise() {
    return new Promise((resolve) => {
        setTimeout(() => resolve(), 0);
    });
}

async function evaluateSimilarityDict(title, dict, results) {
    let i = 0;

    for (const noteId in dict) {
        evaluateSimilarity(title, dict[noteId], noteId, results);

        i++;

        if (i % 200 === 0) {
            await setImmediatePromise();
        }
    }
}

async function findSimilarNotes(title) {
    const results = [];

    await evaluateSimilarityDict(title, noteTitles, results);

    if (protectedSessionService.isProtectedSessionAvailable()) {
        await evaluateSimilarityDict(title, protectedNoteTitles, results);
    }

    results.sort((a, b) => a.coeff > b.coeff ? -1 : 1);

    return results.length > 50 ? results.slice(0, 50) : results;
}

eventService.subscribe([eventService.ENTITY_CHANGED, eventService.ENTITY_DELETED, eventService.ENTITY_SYNCED],  async ({entityName, entity}) => {
    // note that entity can also be just POJO without methods if coming from sync

    if (!loaded) {
        return;
    }

    if (entityName === 'notes') {
        const note = entity;

        if (note.isDeleted) {
            delete noteTitles[note.noteId];
            delete childToParent[note.noteId];
        }
        else {
            if (note.isProtected) {
                // we can assume we have protected session since we managed to update
                // removing from the maps is important when switching between protected & unprotected
                protectedNoteTitles[note.noteId] = note.title;
                delete noteTitles[note.noteId];
            }
            else {
                noteTitles[note.noteId] = note.title;
                delete protectedNoteTitles[note.noteId];
            }
        }
    }
    else if (entityName === 'branches') {
        const branch = entity;

        if (branch.isDeleted) {
            if (branch.noteId in childToParent) {
                childToParent[branch.noteId] = childToParent[branch.noteId].filter(noteId => noteId !== branch.parentNoteId);
            }

            delete prefixes[branch.noteId + '-' + branch.parentNoteId];
            delete childParentToBranchId[branch.noteId + '-' + branch.parentNoteId];
        }
        else {
            if (branch.prefix) {
                prefixes[branch.noteId + '-' + branch.parentNoteId] = branch.prefix;
            }

            childToParent[branch.noteId] = childToParent[branch.noteId] || [];

            if (!childToParent[branch.noteId].includes(branch.parentNoteId)) {
                childToParent[branch.noteId].push(branch.parentNoteId);
            }

            resortChildToParent(branch.noteId);

            childParentToBranchId[branch.noteId + '-' + branch.parentNoteId] = branch.branchId;
        }
    }
    else if (entityName === 'attributes') {
        const attribute = entity;

        if (attribute.type === 'label' && attribute.name === 'archived') {
            // we're not using label object directly, since there might be other non-deleted archived label
            const archivedLabel = await repository.getEntity(`SELECT * FROM attributes WHERE isDeleted = 0 AND type = 'label' 
                                 AND name = 'archived' AND noteId = ?`, [attribute.noteId]);

            if (archivedLabel) {
                archived[attribute.noteId] = archivedLabel.isInheritable ? 1 : 0;
            }
            else {
                delete archived[attribute.noteId];
            }
        }
    }
});

// will sort the childs so that non-archived are first and archived at the end
// this is done so that non-archived paths are always explored as first when searching for note path
function resortChildToParent(noteId) {
    if (!(noteId in childToParent)) {
        return;
    }

    childToParent[noteId].sort((a, b) => archived[a] === 1 ? 1 : -1);
}

/**
 * @param noteId
 * @returns {boolean} - true if note exists (is not deleted) and is available in current note hoisting
 */
function isAvailable(noteId) {
    const notePath = getNotePath(noteId);

    return !!notePath;
}

eventService.subscribe(eventService.ENTER_PROTECTED_SESSION, () => {
    loadedPromise.then(() => decryptProtectedNotes());
});

sqlInit.dbReady.then(() => utils.stopWatch("Note cache load", load));

module.exports = {
    loadedPromise,
    findNotes,
    getNotePath,
    getNoteTitleForPath,
    getNoteTitleFromPath,
    isAvailable,
    isArchived,
    isInAncestor,
    load,
    findSimilarNotes
};