/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import * as objects from 'vs/base/common/objects';
import { parse } from 'vs/base/common/json';
import { values, keys } from 'vs/base/common/map';
import { IUserFriendlyKeybinding } from 'vs/platform/keybinding/common/keybinding';
import { firstIndex as findFirstIndex, equals } from 'vs/base/common/arrays';
import { ContextKeyExpr } from 'vs/platform/contextkey/common/contextkey';
import * as contentUtil from 'vs/platform/userDataSync/common/content';
import { IStringDictionary } from 'vs/base/common/collections';
import { FormattingOptions } from 'vs/base/common/jsonFormatter';
import { IUserDataSyncUtilService } from 'vs/platform/userDataSync/common/userDataSync';

interface ICompareResult {
	added: Set<string>;
	removed: Set<string>;
	updated: Set<string>;
}

interface IMergeResult {
	hasLocalForwarded: boolean;
	hasRemoteForwarded: boolean;
	added: Set<string>;
	removed: Set<string>;
	updated: Set<string>;
	conflicts: Set<string>;
}

export async function merge(localContent: string, remoteContent: string, baseContent: string | null, formattingOptions: FormattingOptions, userDataSyncUtilService: IUserDataSyncUtilService): Promise<{ mergeContent: string, hasChanges: boolean, hasConflicts: boolean }> {
	const local = <IUserFriendlyKeybinding[]>parse(localContent);
	const remote = <IUserFriendlyKeybinding[]>parse(remoteContent);
	const base = baseContent ? <IUserFriendlyKeybinding[]>parse(baseContent) : null;

	const userbindings: string[] = [...local, ...remote, ...(base || [])].map(keybinding => keybinding.key);
	const normalizedKeys = await userDataSyncUtilService.resolveUserBindings(userbindings);
	let keybindingsMergeResult = computeMergeResultByKeybinding(local, remote, base, normalizedKeys);

	if (!keybindingsMergeResult.hasLocalForwarded && !keybindingsMergeResult.hasRemoteForwarded) {
		// No changes found between local and remote.
		return { mergeContent: localContent, hasChanges: false, hasConflicts: false };
	}

	if (!keybindingsMergeResult.hasLocalForwarded && keybindingsMergeResult.hasRemoteForwarded) {
		return { mergeContent: remoteContent, hasChanges: true, hasConflicts: false };
	}

	if (keybindingsMergeResult.hasLocalForwarded && !keybindingsMergeResult.hasRemoteForwarded) {
		// Local has moved forward and remote has not. Return local.
		return { mergeContent: localContent, hasChanges: true, hasConflicts: false };
	}

	// Both local and remote has moved forward.
	const localByCommand = byCommand(local);
	const remoteByCommand = byCommand(remote);
	const baseByCommand = base ? byCommand(base) : null;
	const localToRemoteByCommand = compareByCommand(localByCommand, remoteByCommand, normalizedKeys);
	const baseToLocalByCommand = baseByCommand ? compareByCommand(baseByCommand, localByCommand, normalizedKeys) : { added: keys(localByCommand).reduce((r, k) => { r.add(k); return r; }, new Set<string>()), removed: new Set<string>(), updated: new Set<string>() };
	const baseToRemoteByCommand = baseByCommand ? compareByCommand(baseByCommand, remoteByCommand, normalizedKeys) : { added: keys(remoteByCommand).reduce((r, k) => { r.add(k); return r; }, new Set<string>()), removed: new Set<string>(), updated: new Set<string>() };

	const commandsMergeResult = computeMergeResult(localToRemoteByCommand, baseToLocalByCommand, baseToRemoteByCommand);
	let mergeContent = localContent;

	// Removed commands in Remote
	for (const command of values(commandsMergeResult.removed)) {
		if (commandsMergeResult.conflicts.has(command)) {
			continue;
		}
		mergeContent = removeKeybindings(mergeContent, command, formattingOptions);
	}

	// Added commands in remote
	for (const command of values(commandsMergeResult.added)) {
		if (commandsMergeResult.conflicts.has(command)) {
			continue;
		}
		const keybindings = remoteByCommand.get(command)!;
		// Ignore negated commands
		if (keybindings.some(keybinding => keybinding.command !== `-${command}` && keybindingsMergeResult.conflicts.has(normalizedKeys[keybinding.key]))) {
			commandsMergeResult.conflicts.add(command);
			continue;
		}
		mergeContent = addKeybindings(mergeContent, keybindings, formattingOptions);
	}

	// Updated commands in Remote
	for (const command of values(commandsMergeResult.updated)) {
		if (commandsMergeResult.conflicts.has(command)) {
			continue;
		}
		const keybindings = remoteByCommand.get(command)!;
		// Ignore negated commands
		if (keybindings.some(keybinding => keybinding.command !== `-${command}` && keybindingsMergeResult.conflicts.has(normalizedKeys[keybinding.key]))) {
			commandsMergeResult.conflicts.add(command);
			continue;
		}
		mergeContent = updateKeybindings(mergeContent, command, keybindings, formattingOptions);
	}

	return { mergeContent, hasChanges: true, hasConflicts: commandsMergeResult.conflicts.size > 0 };
}

function computeMergeResult(localToRemote: ICompareResult, baseToLocal: ICompareResult, baseToRemote: ICompareResult): { added: Set<string>, removed: Set<string>, updated: Set<string>, conflicts: Set<string> } {
	const added: Set<string> = new Set<string>();
	const removed: Set<string> = new Set<string>();
	const updated: Set<string> = new Set<string>();
	const conflicts: Set<string> = new Set<string>();

	// Removed keys in Local
	for (const key of values(baseToLocal.removed)) {
		// Got updated in remote
		if (baseToRemote.updated.has(key)) {
			conflicts.add(key);
		}
	}

	// Removed keys in Remote
	for (const key of values(baseToRemote.removed)) {
		if (conflicts.has(key)) {
			continue;
		}
		// Got updated in local
		if (baseToLocal.updated.has(key)) {
			conflicts.add(key);
		} else {
			// remove the key
			removed.add(key);
		}
	}

	// Added keys in Local
	for (const key of values(baseToLocal.added)) {
		if (conflicts.has(key)) {
			continue;
		}
		// Got added in remote
		if (baseToRemote.added.has(key)) {
			// Has different value
			if (localToRemote.updated.has(key)) {
				conflicts.add(key);
			}
		}
	}

	// Added keys in remote
	for (const key of values(baseToRemote.added)) {
		if (conflicts.has(key)) {
			continue;
		}
		// Got added in local
		if (baseToLocal.added.has(key)) {
			// Has different value
			if (localToRemote.updated.has(key)) {
				conflicts.add(key);
			}
		} else {
			added.add(key);
		}
	}

	// Updated keys in Local
	for (const key of values(baseToLocal.updated)) {
		if (conflicts.has(key)) {
			continue;
		}
		// Got updated in remote
		if (baseToRemote.updated.has(key)) {
			// Has different value
			if (localToRemote.updated.has(key)) {
				conflicts.add(key);
			}
		}
	}

	// Updated keys in Remote
	for (const key of values(baseToRemote.updated)) {
		if (conflicts.has(key)) {
			continue;
		}
		// Got updated in local
		if (baseToLocal.updated.has(key)) {
			// Has different value
			if (localToRemote.updated.has(key)) {
				conflicts.add(key);
			}
		} else {
			// updated key
			updated.add(key);
		}
	}
	return { added, removed, updated, conflicts };
}

function computeMergeResultByKeybinding(local: IUserFriendlyKeybinding[], remote: IUserFriendlyKeybinding[], base: IUserFriendlyKeybinding[] | null, normalizedKeys: IStringDictionary<string>): IMergeResult {
	const empty = new Set<string>();
	const localByKeybinding = byKeybinding(local, normalizedKeys);
	const remoteByKeybinding = byKeybinding(remote, normalizedKeys);
	const baseByKeybinding = base ? byKeybinding(base, normalizedKeys) : null;

	const localToRemoteByKeybinding = compareByKeybinding(localByKeybinding, remoteByKeybinding);
	if (localToRemoteByKeybinding.added.size === 0 && localToRemoteByKeybinding.removed.size === 0 && localToRemoteByKeybinding.updated.size === 0) {
		return { hasLocalForwarded: false, hasRemoteForwarded: false, added: empty, removed: empty, updated: empty, conflicts: empty };
	}

	const baseToLocalByKeybinding = baseByKeybinding ? compareByKeybinding(baseByKeybinding, localByKeybinding) : { added: keys(localByKeybinding).reduce((r, k) => { r.add(k); return r; }, new Set<string>()), removed: new Set<string>(), updated: new Set<string>() };
	if (baseToLocalByKeybinding.added.size === 0 && baseToLocalByKeybinding.removed.size === 0 && baseToLocalByKeybinding.updated.size === 0) {
		// Remote has moved forward and local has not.
		return { hasLocalForwarded: false, hasRemoteForwarded: true, added: empty, removed: empty, updated: empty, conflicts: empty };
	}

	const baseToRemoteByKeybinding = baseByKeybinding ? compareByKeybinding(baseByKeybinding, remoteByKeybinding) : { added: keys(remoteByKeybinding).reduce((r, k) => { r.add(k); return r; }, new Set<string>()), removed: new Set<string>(), updated: new Set<string>() };
	if (baseToRemoteByKeybinding.added.size === 0 && baseToRemoteByKeybinding.removed.size === 0 && baseToRemoteByKeybinding.updated.size === 0) {
		return { hasLocalForwarded: true, hasRemoteForwarded: false, added: empty, removed: empty, updated: empty, conflicts: empty };
	}

	const { added, removed, updated, conflicts } = computeMergeResult(localToRemoteByKeybinding, baseToLocalByKeybinding, baseToRemoteByKeybinding);
	return { hasLocalForwarded: true, hasRemoteForwarded: true, added, removed, updated, conflicts };
}

function byKeybinding(keybindings: IUserFriendlyKeybinding[], keys: IStringDictionary<string>) {
	const map: Map<string, IUserFriendlyKeybinding[]> = new Map<string, IUserFriendlyKeybinding[]>();
	for (const keybinding of keybindings) {
		const key = keys[keybinding.key];
		let value = map.get(key);
		if (!value) {
			value = [];
			map.set(key, value);
		}
		value.push(keybinding);

	}
	return map;
}

function byCommand(keybindings: IUserFriendlyKeybinding[]): Map<string, IUserFriendlyKeybinding[]> {
	const map: Map<string, IUserFriendlyKeybinding[]> = new Map<string, IUserFriendlyKeybinding[]>();
	for (const keybinding of keybindings) {
		const command = keybinding.command[0] === '-' ? keybinding.command.substring(1) : keybinding.command;
		let value = map.get(command);
		if (!value) {
			value = [];
			map.set(command, value);
		}
		value.push(keybinding);
	}
	return map;
}


function compareByKeybinding(from: Map<string, IUserFriendlyKeybinding[]>, to: Map<string, IUserFriendlyKeybinding[]>): ICompareResult {
	const fromKeys = keys(from);
	const toKeys = keys(to);
	const added = toKeys.filter(key => fromKeys.indexOf(key) === -1).reduce((r, key) => { r.add(key); return r; }, new Set<string>());
	const removed = fromKeys.filter(key => toKeys.indexOf(key) === -1).reduce((r, key) => { r.add(key); return r; }, new Set<string>());
	const updated: Set<string> = new Set<string>();

	for (const key of fromKeys) {
		if (removed.has(key)) {
			continue;
		}
		const value1: IUserFriendlyKeybinding[] = from.get(key)!.map(keybinding => ({ ...keybinding, ...{ key } }));
		const value2: IUserFriendlyKeybinding[] = to.get(key)!.map(keybinding => ({ ...keybinding, ...{ key } }));
		if (!equals(value1, value2, (a, b) => isSameKeybinding(a, b))) {
			updated.add(key);
		}
	}

	return { added, removed, updated };
}

function compareByCommand(from: Map<string, IUserFriendlyKeybinding[]>, to: Map<string, IUserFriendlyKeybinding[]>, normalizedKeys: IStringDictionary<string>): ICompareResult {
	const fromKeys = keys(from);
	const toKeys = keys(to);
	const added = toKeys.filter(key => fromKeys.indexOf(key) === -1).reduce((r, key) => { r.add(key); return r; }, new Set<string>());
	const removed = fromKeys.filter(key => toKeys.indexOf(key) === -1).reduce((r, key) => { r.add(key); return r; }, new Set<string>());
	const updated: Set<string> = new Set<string>();

	for (const key of fromKeys) {
		if (removed.has(key)) {
			continue;
		}
		const value1: IUserFriendlyKeybinding[] = from.get(key)!.map(keybinding => ({ ...keybinding, ...{ key: normalizedKeys[keybinding.key] } }));
		const value2: IUserFriendlyKeybinding[] = to.get(key)!.map(keybinding => ({ ...keybinding, ...{ key: normalizedKeys[keybinding.key] } }));
		if (!areSameKeybindingsWithSameCommand(value1, value2)) {
			updated.add(key);
		}
	}

	return { added, removed, updated };
}

function areSameKeybindingsWithSameCommand(value1: IUserFriendlyKeybinding[], value2: IUserFriendlyKeybinding[]): boolean {
	// Compare entries adding keybindings
	if (!equals(value1.filter(({ command }) => command[0] !== '-'), value2.filter(({ command }) => command[0] !== '-'), (a, b) => isSameKeybinding(a, b))) {
		return false;
	}
	// Compare entries removing keybindings
	if (!equals(value1.filter(({ command }) => command[0] === '-'), value2.filter(({ command }) => command[0] === '-'), (a, b) => isSameKeybinding(a, b))) {
		return false;
	}
	return true;
}

function isSameKeybinding(a: IUserFriendlyKeybinding, b: IUserFriendlyKeybinding): boolean {
	if (a.command !== b.command) {
		return false;
	}
	if (a.key !== b.key) {
		return false;
	}
	const whenA = ContextKeyExpr.deserialize(a.when);
	const whenB = ContextKeyExpr.deserialize(b.when);
	if ((whenA && !whenB) || (!whenA && whenB)) {
		return false;
	}
	if (whenA && whenB && !whenA.equals(whenB)) {
		return false;
	}
	if (!objects.equals(a.args, b.args)) {
		return false;
	}
	return true;
}

function addKeybindings(content: string, keybindings: IUserFriendlyKeybinding[], formattingOptions: FormattingOptions): string {
	for (const keybinding of keybindings) {
		content = contentUtil.edit(content, [-1], keybinding, formattingOptions);
	}
	return content;
}

function removeKeybindings(content: string, command: string, formattingOptions: FormattingOptions): string {
	const keybindings = <IUserFriendlyKeybinding[]>parse(content);
	for (let index = keybindings.length - 1; index >= 0; index--) {
		if (keybindings[index].command === command || keybindings[index].command === `-${command}`) {
			content = contentUtil.edit(content, [index], undefined, formattingOptions);
		}
	}
	return content;
}

function updateKeybindings(content: string, command: string, keybindings: IUserFriendlyKeybinding[], formattingOptions: FormattingOptions): string {
	const allKeybindings = <IUserFriendlyKeybinding[]>parse(content);
	const location = findFirstIndex(allKeybindings, keybinding => keybinding.command === command || keybinding.command === `-${command}`);
	// Remove all entries with this command
	for (let index = allKeybindings.length - 1; index >= 0; index--) {
		if (allKeybindings[index].command === command || allKeybindings[index].command === `-${command}`) {
			content = contentUtil.edit(content, [index], undefined, formattingOptions);
		}
	}
	// add all entries at the same location where the entry with this command was located.
	for (let index = keybindings.length - 1; index >= 0; index--) {
		content = contentUtil.edit(content, [location], keybindings[index], formattingOptions);
	}
	return content;
}