import type { Completion, CompletionContext, CompletionResult } from '@codemirror/autocomplete';
import { autocompletion } from '@codemirror/autocomplete';
import { localCompletionSource } from '@codemirror/lang-javascript';
import type { Extension } from '@codemirror/state';
import type { MaybeRefOrGetter } from 'vue';
import { toValue } from 'vue';

import { useBaseCompletions } from './completions/base.completions';
import { jsSnippets } from './completions/js.snippets';

import type { EditorView } from '@codemirror/view';
import type { CodeExecutionMode } from 'n8n-workflow';
import { useExecutionCompletions } from './completions/execution.completions';
import { useItemFieldCompletions } from './completions/itemField.completions';
import { useItemIndexCompletions } from './completions/itemIndex.completions';
import { useJsonFieldCompletions } from './completions/jsonField.completions';
import { useLuxonCompletions } from './completions/luxon.completions';
import { usePrevNodeCompletions } from './completions/prevNode.completions';
import { useRequireCompletions } from './completions/require.completions';
import { useVariablesCompletions } from '@/features/settings/environments.ee/completions/variables.completions';
import { useWorkflowCompletions } from './completions/workflow.completions';

export const useCompleter = (
	mode: MaybeRefOrGetter<CodeExecutionMode>,
	editor: MaybeRefOrGetter<EditorView | null>,
) => {
	function autocompletionExtension(language: 'javaScript' | 'python' | 'pythonNative'): Extension {
		if (language === 'pythonNative') {
			const completions = (context: CompletionContext): CompletionResult | null => {
				const word = context.matchBefore(/\w*/);
				if (!word) return null;

				const options = [];

				const label = toValue(mode) === 'runOnceForEachItem' ? '_item' : '_items';
				options.push({ label, type: 'variable' });
				options.push({ label: 'print', type: 'function' });

				return { from: word.from, options };
			};

			return autocompletion({ icons: false, override: [completions] });
		}

		// Base completions
		const { baseCompletions, itemCompletions, nodeSelectorCompletions } = useBaseCompletions(
			toValue(mode),
			language,
		);
		const { executionCompletions } = useExecutionCompletions();
		const { inputMethodCompletions, selectorMethodCompletions } = useItemFieldCompletions(language);
		const { inputCompletions, selectorCompletions } = useItemIndexCompletions(mode);
		const { inputJsonFieldCompletions, selectorJsonFieldCompletions } = useJsonFieldCompletions();
		const { dateTimeCompletions, nowCompletions, todayCompletions } = useLuxonCompletions();
		const { prevNodeCompletions } = usePrevNodeCompletions();
		const { requireCompletions } = useRequireCompletions();
		const { variablesCompletions } = useVariablesCompletions();
		const { workflowCompletions } = useWorkflowCompletions();

		const completions = [];
		if (language === 'javaScript') {
			completions.push(jsSnippets, localCompletionSource);
		}

		return autocompletion({
			icons: false,
			compareCompletions: (a: Completion, b: Completion) => {
				if (/\.json$|id$|id['"]\]$/.test(a.label)) return 0;

				return a.label.localeCompare(b.label);
			},
			override: [
				...completions,

				// core
				itemCompletions,
				baseCompletions,
				requireCompletions,
				nodeSelectorCompletions,
				prevNodeCompletions,
				workflowCompletions,
				variablesCompletions,
				executionCompletions,

				// luxon
				todayCompletions,
				nowCompletions,
				dateTimeCompletions,

				// item index
				inputCompletions,
				selectorCompletions,

				// item field
				inputMethodCompletions,
				selectorMethodCompletions,

				// item json field
				inputJsonFieldCompletions,
				selectorJsonFieldCompletions,

				// multiline
				multilineCompletions,
			],
		});
	}

	/**
	 * Complete uses of variables to any of the supported completions.
	 */
	function multilineCompletions(context: CompletionContext): CompletionResult | null {
		const editorValue = toValue(editor);
		if (!editorValue) return null;

		let variablesToValueMap: Record<string, string> = {};

		try {
			variablesToValueMap = variablesToValues();
		} catch {
			return null;
		}

		if (Object.keys(variablesToValueMap).length === 0) return null;

		/**
		 * Complete uses of extended variables, i.e. variables having
		 * one or more dotted segments already.
		 *
		 * const x = $input;
		 * x.first(). -> .json
		 * x.first().json. -> .field
		 */

		const docLines = editorValue.state.doc.toString().split('\n');

		const varNames = Object.keys(variablesToValueMap);

		const uses = extendedUses(docLines, varNames);
		const { matcherItemFieldCompletions } = useItemFieldCompletions('javaScript');
		for (const use of uses.itemField) {
			const matcher = use.replace(/\.$/, '');
			const completions = matcherItemFieldCompletions(context, matcher, variablesToValueMap);

			if (completions) return completions;
		}

		for (const use of uses.jsonField) {
			const matcher = use.replace(/(\.|\[)$/, '');
			const completions = matcherItemFieldCompletions(context, matcher, variablesToValueMap);

			if (completions) return completions;
		}

		/**
		 * Complete uses of unextended variables, i.e. variables having
		 * no dotted segment already.
		 *
		 * const x = $input;
		 * x. -> .first()
		 *
		 * const x = $input.first();
		 * x. -> .json
		 *
		 * const x = $input.first().json;
		 * x. -> .field
		 */

		const SELECTOR_REGEX = /^\$\((?<quotedNodeName>['"][\w\s]+['"])\)$/; // $('nodeName')

		const INPUT_METHOD_REGEXES = Object.values({
			first: /\$input\.first\(\)$/,
			last: /\$input\.last\(\)$/,
			item: /\$input\.item$/,
			all: /\$input\.all\(\)\[(?<index>\w+)\]$/,
		});

		const SELECTOR_METHOD_REGEXES = Object.values({
			first: /\$\((?<quotedNodeName>['"][\w\s]+['"])\)\.first\(\)$/,
			last: /\$\((?<quotedNodeName>['"][\w\s]+['"])\)\.last\(\)$/,
			item: /\$\((?<quotedNodeName>['"][\w\s]+['"])\)\.item$/,
			all: /\$\((?<quotedNodeName>['"][\w\s]+['"])\)\.all\(\)\[(?<index>\w+)\]$/,
		});

		const INPUT_JSON_REGEXES = Object.values({
			first: /\$input\.first\(\)\.json$/,
			last: /\$input\.last\(\)\.json$/,
			item: /\$input\.item\.json$/,
			all: /\$input\.all\(\)\[(?<index>\w+)\]\.json$/,
		});

		const SELECTOR_JSON_REGEXES = Object.values({
			first: /\$\((?<quotedNodeName>['"][\w\s]+['"])\)\.first\(\)\.json$/,
			last: /\$\((?<quotedNodeName>['"][\w\s]+['"])\)\.last\(\)\.json$/,
			item: /\$\((?<quotedNodeName>['"][\w\s]+['"])\)\.item\.json$/,
			all: /\$\((?<quotedNodeName>['"][\w\s]+['"])\)\.all\(\)\[(?<index>\w+)\]\.json$/,
		});

		const { executionCompletions } = useExecutionCompletions();
		const { inputCompletions, selectorCompletions } = useItemIndexCompletions(mode);
		const { matcherJsonFieldCompletions } = useJsonFieldCompletions();
		const { dateTimeCompletions, nowCompletions, todayCompletions } = useLuxonCompletions();
		const { variablesCompletions } = useVariablesCompletions();
		const { workflowCompletions } = useWorkflowCompletions();

		for (const [variable, value] of Object.entries(variablesToValueMap)) {
			const { prevNodeCompletions } = usePrevNodeCompletions(variable);

			if (value === '$execution') return executionCompletions(context, variable);
			if (value === '$vars') return variablesCompletions(context, variable);

			if (value === '$workflow') return workflowCompletions(context, variable);
			if (value === '$prevNode') return prevNodeCompletions(context);

			// luxon

			if (value === '$now') return nowCompletions(context, variable);
			if (value === '$today') return todayCompletions(context, variable);
			if (value === 'DateTime') return dateTimeCompletions(context, variable);

			// item index

			if (value === '$input') return inputCompletions(context, variable);
			if (SELECTOR_REGEX.test(value)) return selectorCompletions(context, variable);

			// json field

			const inputJsonMatched = INPUT_JSON_REGEXES.some((regex) => regex.test(value));
			const selectorJsonMatched = SELECTOR_JSON_REGEXES.some((regex) => regex.test(value));

			if (inputJsonMatched || selectorJsonMatched) {
				return matcherJsonFieldCompletions(context, variable, variablesToValueMap);
			}

			// item field

			const inputMethodMatched = INPUT_METHOD_REGEXES.some((regex) => regex.test(value));
			const selectorMethodMatched = SELECTOR_METHOD_REGEXES.some((regex) => regex.test(value));

			if (inputMethodMatched || selectorMethodMatched) {
				return matcherItemFieldCompletions(context, variable, variablesToValueMap);
			}
		}

		return null;
	}

	// ----------------------------------
	//            helpers
	// ----------------------------------

	/**
	 * Create a map of variables and the values they point to.
	 */
	function variablesToValues() {
		return variableDeclarationLines().reduce<Record<string, string>>((acc, line) => {
			const [left, right] = line.split('=');

			const varName = left.replace(/(var|let|const)/, '').trim();
			const varValue = right.replace(/;/, '').trim();

			acc[varName] = varValue;

			return acc;
		}, {});
	}

	function variableDeclarationLines() {
		const editorValue = toValue(editor);
		if (!editorValue) return [];

		const docLines = editorValue.state.doc.toString().split('\n');

		const isVariableDeclarationLine = (line: string) =>
			['var', 'const', 'let'].some((varType) => line.startsWith(varType));

		return docLines.filter(isVariableDeclarationLine);
	}

	/**
	 * Collect uses of variables pointing to n8n syntax if they have been extended.
	 *
	 * x.first().
	 * x.first().json.
	 * x.json.
	 */
	function extendedUses(docLines: string[], varNames: string[]) {
		return docLines.reduce<{ itemField: string[]; jsonField: string[] }>(
			(acc, cur) => {
				varNames.forEach((varName) => {
					const accessorPattern = `(${varName}.first\\(\\)|${varName}.last\\(\\)|${varName}.item|${varName}.all\\(\\)\\[\\w+\\]).*`;

					const methodMatch = cur.match(new RegExp(accessorPattern));

					if (methodMatch) {
						if (/json(\.|\[)$/.test(methodMatch[0])) {
							acc.jsonField.push(methodMatch[0]);
						} else {
							acc.itemField.push(methodMatch[0]);
						}
					}

					const jsonPattern = `^${varName}\\.json(\\.|\\[)$`;

					const jsonMatch = cur.match(new RegExp(jsonPattern));

					if (jsonMatch) {
						acc.jsonField.push(jsonMatch[0]);
					}
				});

				return acc;
			},
			{ itemField: [], jsonField: [] },
		);
	}

	return { autocompletionExtension };
};
