pragma Singleton

import "../../scripts/fzf.js" as Fzf
import QtQuick
import Quickshell
import ZShell
import qs.Config

// Search service over the settings index. The index is generated at build time
// from the page QML files by scripts/build-settings-index.py and baked into the
// plugin binary (read via CUtils.settingsIndex), so it stays in sync with the UI
// without any hand-maintained entries and without a user-editable data file.
//
// Unlike the launcher's fuzzy searcher, this uses the real inverted index +
// ranking baked into the JSON: a query is tokenised, each token is looked up in
// the inverted index (exact token or prefix), the matching entry ids are scored
// with the precomputed per-token ranking, and the best entries are returned.
// SettingEntry QObjects are produced via Variants so the result objects expose
// the same properties the result list expects.
Singleton {
	id: root

	// fzf finder over the entries (title + keywords), used as a fuzzy fallback
	// when the exact/prefix index lookup comes up short. fzf is the same matcher
	// the launcher uses, so typo and mid-word matching behave consistently.
	property var fzfFinder: null

	// entries: forward index (one record per setting)
	// inverted: token -> [entry id...]
	// ranking:  token -> { entry id (string): weight }
	property var inverted: ({})
	property var ranking: ({})

	// Wrap the parts of `text` that match the search in the given colour, for use
	// with a StyledText in Text.StyledText format. Matches each query token as a
	// prefix at a word boundary (mirroring how lookup matches), so "wall"
	// highlights the start of "wallpaper". StyledText supports <font color> but
	// not CSS <span style>. HTML-significant characters are escaped first so the
	// rich-text parser doesn't choke on names with & < or >.
	function highlight(text: string, search: string, colour: color): string {
		const escaped = text.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;");
		const tokens = tokenize(search);
		if (tokens.length === 0)
			return escaped;
		const escapedTokens = tokens.map(t => t.replace(/[.*+?^${}()|[\]\\]/g, "\\$&"));
		const pattern = new RegExp("\\b(" + escapedTokens.join("|") + ")", "gi");
		return escaped.replace(pattern, `<font color="${colour}">$1</font>`);
	}

	// Look up a query token in the inverted index: exact match first, then any
	// indexed token that starts with it (prefix search, so "wif" finds "wifi").
	// Returns a map of entry id -> best ranking weight for that id.
	function lookup(token: string): var {
		const result = ({});
		const exact = root.inverted[token] !== undefined;
		const keys = exact ? [token] : Object.keys(root.inverted).filter(k => k.startsWith(token));
		for (const key of keys) {
			const rank = root.ranking[key] ?? ({});
			for (const id of root.inverted[key]) {
				const w = rank[id] ?? 0.1;
				if (result[id] === undefined || w > result[id])
					result[id] = w;
			}
		}

		return result;
	}

	function query(search: string): list<QtObject> {
		const tokens = root.tokenize(search);
		if (tokens.length === 0)
			return [];

		// Accumulate a score per entry id across all query tokens. An entry must
		// match every query token (AND), and its score is the sum of the ranking
		// weights of the index tokens it matched, so results stay relevant.
		const scores = ({});
		const hitCounts = ({});
		for (const token of tokens) {
			const matches = root.lookup(token); // { id: weight }
			for (const id in matches) {
				scores[id] = (scores[id] ?? 0) + matches[id];
				hitCounts[id] = (hitCounts[id] ?? 0) + 1;
			}
		}

		// Sort by score, breaking ties by id so the order is stable (otherwise
		// entries with equal scores can be dropped arbitrarily by the limit).
		const ranked = Object.keys(scores).filter(id => hitCounts[id] === tokens.length).sort((a, b) => scores[b] - scores[a] || (parseInt(a) - parseInt(b))).slice(0, 25);

		const all = entries.instances;
		const out = ranked.map(id => all[parseInt(id)]).filter(e => e !== undefined);

		// The inverted index only does exact/prefix matches. When it finds little
		// or nothing - a typo ("trasparency") or a mid-word query ("paper") - fall
		// back to fzf over the same entries. fzf hits that the index already
		// returned are skipped, and the rest are appended after the (stronger)
		// index results, so precise matches always lead.
		if (out.length < 5 && root.fzfFinder) {
			const seen = ({});
			for (const id of ranked)
				seen[id] = true;
			const fuzzy = root.fzfFinder.find(search);
			for (const r of fuzzy) {
				const idx = r.item.idx;
				if (seen[idx])
					continue;
				seen[idx] = true;
				const entry = all[idx];
				if (entry !== undefined)
					out.push(entry);
				if (out.length >= 25)
					break;
			}
		}

		return out;
	}

	function tokenize(text: string): var {
		return text.toLowerCase().split(/[^a-z0-9]+/).filter(t => t.length > 0);
	}

	Component.onCompleted: {
		try {
			const data = JSON.parse(ZUtils.settingsIndex());
			entries.model = data.entries;
			root.inverted = data.inverted ?? {};
			root.ranking = data.ranking ?? {};
			// One searchable string per entry: the title. fzf provides typo and
			// mid-word matching over titles as a fallback when the exact/prefix
			// index lookup comes up short.
			const docs = data.entries.map((e, i) => ({
						idx: i,
						text: e.title
					}));
			root.fzfFinder = new Fzf.Finder(docs, {
				selector: d => d.text,
				limit: 25
			});
		} catch (e) {
			entries.model = [];
			root.inverted = {};
			root.ranking = {};
			root.fzfFinder = null;
		}
	}

	Variants {
		id: entries

		SettingEntry {
		}
	}

	component SettingEntry: QtObject {
		readonly property string anchor: modelData.anchor ?? ""
		readonly property var crumbIcons: modelData.crumbIcons
		readonly property var crumbLabels: modelData.crumbLabels
		readonly property bool isToggle: togglePath.length > 0
		required property var modelData
		readonly property int pageIdx: modelData.pageIdx
		readonly property string section: modelData.section ?? ""
		readonly property var subPath: modelData.subPath
		readonly property string subtext: modelData.subtext ?? ""
		readonly property string title: modelData.title

		// A non-empty togglePath means this is a plain on/off setting that can be
		// flipped straight from the results (e.g. "background.wallpaperEnabled").
		readonly property string togglePath: modelData.togglePath ?? ""
		// Live value of the config property, read by walking the path on
		// GlobalConfig. Re-evaluates when that property changes.
		readonly property bool toggleValue: {
			if (!isToggle)
				return false;
			let obj = Config;
			const parts = togglePath.split(".");
			for (const part of parts) {
				if (obj === undefined || obj === null)
					return false;
				obj = obj[part];
			}
			return obj ?? false;
		}

		// Write `value` back to the config property the path points at.
		function setToggle(value: bool): void {
			if (!isToggle)
				return;
			const parts = togglePath.split(".");
			let obj = Config;
			for (let k = 0; k < parts.length - 1; k++) {
				if (obj === undefined || obj === null)
					return;
				obj = obj[parts[k]];
			}
			if (obj !== undefined && obj !== null)
				obj[parts[parts.length - 1]] = value;
		}
	}
}