/**
 * resolveSignature(signal, opts) — turns a `SemanticSignal` into the
 * per-channel `EffectiveSignature` used by every channel.
 *
 * Resolution cascade (each layer overrides the previous):
 *
 *   1. FAMILY base       — `SEMA_MAP.families[signal.family].base`
 *   2. INTENT deltas     — `SEMA_MAP.intents[signal.intent]` when present
 *   3. soundPack URL     — `SEMA_MAP.soundPack[<family>-<intent>]`
 *   4. MORFO overrides   — `signal.overrides` / `signal.channels`
 *                          (from the morfo event, copied by SomaRuntime)
 *   5. RUNTIME overrides — `options.runtimeMap` already has
 *                          `engineOpts.overrides.runtime` baked in by the
 *                          engine via `applyMapOverrides()` at construction
 *   6. CASCADE rules     — `options.cascade` — CSS-style rules matched
 *                          against `signal.target` AFTER the engine has
 *                          stamped `data-event-*` on it (see `stamp.ts`).
 *                          Rules are flat: `{ selector, priority?,
 *                          channels?, sound?, haptic? }`. The selector is
 *                          matched natively via `target.matches()` /
 *                          `target.closest()`.
 *
 * CSS-like specificity orders cascade rules: ascending order — later
 * applied wins. Authors can override with `priority?: number` (replaces
 * the computed specificity entirely).
 *
 * Pure function — `resolveSignature` reads from `SEMA_MAP` (or a passed
 * map) and an optional immutable `cascade` array. Runtime path overrides
 * are baked into the map up-front by the engine via `applyMapOverrides`,
 * so this function never mutates anything.
 */

import type { SemanticSignal } from './signal';
import type { Intent } from '../intent';
import type { SemaFamily } from './types';
import { resolveSemaDuration } from './durations';
import {
	SEMA_MAP,
	SEMA_VALENCED_FAMILY_LIST,
	type DeltaOp,
	type DeltaValue,
	type HapticSignature,
	type SemaChannelId,
	type SemaChannelSignatures,
	type SemaMap,
	type SemaSignatureOverride,
	type SoundSignature
} from './sema-map';

export type {
	HapticSignature,
	SemaChannelId,
	SemaChannelSignatures,
	SemaSignatureOverride,
	SoundSignature
} from './sema-map';

/**
 * Single cascade rule. Identical shape to a CSS rule — a selector that
 * matches the target's data-attrs (state from morfo + event tokens
 * stamped by the engine) and a flat block of per-channel deltas.
 *
 *   {
 *     selector: '[data-dialog-content][data-event-intent="threat"]',
 *     sound:  { sampleUrl: '/sounds/dialog-fail.wav' },
 *     haptic: { kind: 'error' }
 *   }
 *
 * No `overrides: { eventLabel: ... }` middle layer — semantic event
 * identity is matched via `[data-event="..."]`,
 * `[data-event-family="..."]` or `[data-event-intent="..."]` directly in
 * the selector.
 */
export interface SemaCascadeRule extends SemaSignatureOverride {
	selector: string;
	/**
	 * Override CSS-computed specificity. When omitted, specificity is
	 * computed from the selector (IDs × 100, attrs / classes /
	 * pseudo-classes × 10, elements × 1). Use `priority` for cases that
	 * need to win without selector gymnastics — typically accessibility
	 * (`priority: 100+`) or experimental cohort overrides.
	 */
	priority?: number;
}

export interface SemaResolveOptions {
	map?: SemaMap;
	cascade?: readonly SemaCascadeRule[];
}

export interface EffectiveSignature {
	family: SemaFamily | undefined;
	intent: Intent | undefined;
	activeChannels: readonly SemaChannelId[];
	/**
	 * Resolved hold duration in ms — how long `data-event-*` tokens live
	 * on the target. Computed from `signal.hold ?? family.hold`. Distinct
	 * from visual motion timing, which lives in Eidos recipes.
	 */
	hold?: number;
	sound?: SoundSignature;
	haptic?: HapticSignature;
}

/** Empty signature returned when input has no family — channels skip. */
const EMPTY_SIGNATURE: EffectiveSignature = {
	family: undefined,
	intent: undefined,
	activeChannels: []
};

export function resolveSignature(
	signal: SemanticSignal,
	mapOrOptions: SemaMap | SemaResolveOptions = SEMA_MAP
): EffectiveSignature {
	const options: SemaResolveOptions = isResolveOptions(mapOrOptions)
		? mapOrOptions
		: { map: mapOrOptions };
	const map = options.map ?? SEMA_MAP;

	if (!signal.family) return EMPTY_SIGNATURE;

	const familyEntry = map.families[signal.family];
	if (!familyEntry) return EMPTY_SIGNATURE;

	// Layer 1 — family base
	// `hold` is resolved up-front: per-call `signal.hold` wins, otherwise
	// the family-declared `hold` from `SEMA_MAP`. Cascade rules can
	// override `hold` directly via the `hold` field on the rule (treated
	// the same as any other channel-less primitive in `applyOverride`).
	const familyHoldMs = resolveSemaDuration(familyEntry.hold);
	const initialHold = signal.hold ?? familyHoldMs;
	let signature: EffectiveSignature = {
		family: signal.family,
		intent: signal.intent,
		activeChannels: [...familyEntry.activeChannels],
		...(initialHold !== undefined ? { hold: initialHold } : {}),
		...cloneBase(familyEntry.base)
	};

	// Layer 2 — intent deltas. Applied whenever the signal carries an
	// intent, regardless of family. The doctrine originally restricted
	// this to valenced families (contact / commit / signal / handle) but
	// real UX needs intent on transitional events too: a `<Dialog
	// intent="threat">` should sound threatening even on the `open` event
	// (emerge family). SomaRuntime forwards the consumer's intent prop
	// when the morfo doesn't declare its own, and the resolver applies
	// the deltas to whichever channels the family's base populated.
	if (signal.intent) {
		const intentEntry = map.intents[signal.intent];
		if (intentEntry) {
			signature = applyChannelDeltas(signature, intentEntry.deltas);
		}
	}

	// Layer 3 — soundPack URL by canonical event label
	const eventLabel = composeEventLabel(signal.family, signal.intent);
	const sampleUrl = map.soundPack[eventLabel];
	if (sampleUrl && signature.sound) {
		signature.sound.sampleUrl = sampleUrl;
	}

	// Layer 4 — per-event morfo overrides (carried by the signal)
	if (signal.channels !== undefined) {
		signature.activeChannels = [...signal.channels];
	}
	if (signal.overrides) {
		signature = applyOverride(signature, signal.overrides);
	}

	// Layer 6 — CSS-style cascade. Rules are matched via target.matches()
	// — channel prepare hooks have already projected `data-event-*` on the
	// target, so selectors that read those tokens match correctly.
	if (options.cascade && options.cascade.length > 0 && signal.target) {
		const matched = collectCascadeMatches(options.cascade, signal.target);
		for (const rule of matched) {
			signature = applyOverride(signature, ruleAsOverride(rule));
		}
	}

	return signature;
}

// ── Cascade matching (CSS-like) ───────────────────────────────────────────

function collectCascadeMatches(
	rules: readonly SemaCascadeRule[],
	target: HTMLElement
): SemaCascadeRule[] {
	const indexed = rules.map((rule, index) => ({
		rule,
		index,
		score: rule.priority ?? cssSpecificity(rule.selector)
	}));

	const matched = indexed.filter(({ rule }) => safeMatches(target, rule.selector));

	// Ascending — last applied wins.
	matched.sort((a, b) => {
		if (a.score !== b.score) return a.score - b.score;
		return a.index - b.index;
	});

	return matched.map(({ rule }) => rule);
}

function safeMatches(target: HTMLElement, selector: string): boolean {
	if (selector === '*') return true;
	try {
		return target.matches(selector) || target.closest(selector) !== null;
	} catch {
		return false;
	}
}

/**
 * Approximate CSS specificity. IDs × 100, attribute selectors / classes /
 * pseudo-classes × 10, element / pseudo-element × 1. Doesn't model the
 * full CSS algorithm (combinators, `:where()`, `:is()`) but suffices for
 * the selector vocabulary cascade rules use in practice.
 */
function cssSpecificity(selector: string): number {
	let score = 0;
	const idMatches = selector.match(/#[\w-]+/g);
	score += 100 * (idMatches?.length ?? 0);
	const attrMatches = selector.match(/\[[^\]]+\]/g);
	score += 10 * (attrMatches?.length ?? 0);
	const classMatches = selector.match(/\.[\w-]+/g);
	score += 10 * (classMatches?.length ?? 0);
	// Pseudo-classes — exclude pseudo-elements (::after etc).
	const pseudoMatches = selector.match(/(?<!:):[\w-]+(?:\([^)]*\))?/g);
	score += 10 * (pseudoMatches?.length ?? 0);
	return score;
}

function ruleAsOverride(rule: SemaCascadeRule): SemaSignatureOverride {
	const { selector: _s, priority: _p, ...override } = rule;
	void _s;
	void _p;
	return override as SemaSignatureOverride;
}

// ── Override application (layers 4 + 6) ───────────────────────────────────
//
// Overrides use REPLACE-by-default for primitive leaves (numbers, strings,
// booleans). Matches CSS intuition: `sound: { gain: 0.4 }` SETS gain to
// 0.4. To explicitly add, use `{ op: 'add', value: 0.1 }`.

function applyOverride(
	signature: EffectiveSignature,
	override: SemaSignatureOverride
): EffectiveSignature {
	const next: EffectiveSignature = deepClone(signature);

	if (override.channels !== undefined) {
		next.activeChannels = [...override.channels];
	}

	for (const key of Object.keys(override)) {
		if (key === 'channels') continue;
		const delta = (override as Record<string, unknown>)[key];
		if (delta === undefined) continue;
		const current = (next as unknown as Record<string, unknown>)[key];
		if (current === undefined) {
			if (isRecord(delta) && !isDeltaOp(delta)) {
				(next as unknown as Record<string, unknown>)[key] = deepClone(delta);
			}
			continue;
		}
		(next as unknown as Record<string, unknown>)[key] = applyLeaf(
			current,
			delta as DeltaValue,
			'replace'
		);
	}

	return next;
}

// ── Channel deltas (layer 2 — intent) ─────────────────────────────────────
//
// Intent deltas use ADD-by-default for numbers — they're modifiers
// composed on top of the family base. Strings/arrays still replace, ops
// take explicit precedence.

function applyChannelDeltas(
	signature: EffectiveSignature,
	deltas: Partial<Record<SemaChannelId, Record<string, DeltaValue>>>
): EffectiveSignature {
	const next: EffectiveSignature = deepClone(signature);
	for (const channel of next.activeChannels) {
		const delta = deltas[channel];
		if (!delta) continue;
		const current = (next as unknown as Record<string, unknown>)[channel as string];
		if (!current) continue;
		(next as unknown as Record<string, unknown>)[channel as string] = applyLeaf(
			current,
			delta,
			'add'
		);
	}
	return next;
}

// ── Internals ──────────────────────────────────────────────────────────────

function isResolveOptions(value: unknown): value is SemaResolveOptions {
	return isRecord(value) && !('families' in value && 'intents' in value);
}

function composeEventLabel(family: SemaFamily, intent?: Intent): string {
	return intent ? `${family}-${intent}` : family;
}

function cloneBase(base: Partial<SemaChannelSignatures>): Partial<SemaChannelSignatures> {
	const out: Partial<SemaChannelSignatures> = {};
	for (const key of Object.keys(base) as (keyof SemaChannelSignatures)[]) {
		const value = base[key];
		if (value !== undefined && value !== null) {
			(out as Record<string, unknown>)[key] = deepClone(value);
		}
	}
	return out;
}

function deepClone<T>(value: T): T {
	return structuredClone(value);
}

function isRecord(value: unknown): value is Record<string, unknown> {
	return value !== null && typeof value === 'object' && !Array.isArray(value);
}

function isDeltaOp(value: unknown): value is DeltaOp {
	return isRecord(value) && typeof value.op === 'string';
}

function applyLeaf(
	base: unknown,
	delta: DeltaValue,
	numberMode: 'add' | 'replace' = 'add'
): unknown {
	if (typeof delta === 'number') {
		if (numberMode === 'replace') return delta;
		return typeof base === 'number' ? base + delta : delta;
	}
	if (typeof delta === 'string' || typeof delta === 'boolean' || delta === null) {
		return delta;
	}
	if (Array.isArray(delta)) {
		return [...delta] as unknown;
	}
	if (isDeltaOp(delta)) {
		if (delta.op === 'replace') {
			return Array.isArray(delta.value) ? [...delta.value] : delta.value;
		}
		if (typeof base !== 'number') return base;
		if (delta.op === 'multiply') return base * delta.factor;
		return base + delta.value;
	}
	if (!isRecord(delta)) return base;
	if (!isRecord(base)) {
		return deepClone(delta);
	}

	const out: Record<string, unknown> = deepClone(base);
	for (const [key, nextDelta] of Object.entries(delta)) {
		out[key] = applyLeaf(out[key], nextDelta as DeltaValue, numberMode);
	}
	return out;
}

// ── Runtime path-based map mutation (layer 5) ─────────────────────────────

/**
 * Apply path-based runtime overrides to the SemaMap, producing a new map
 * without mutating the canonical one. Used by the engine at construction.
 */
export function applyMapOverrides(
	baseMap: SemaMap,
	overrides: Record<string, DeltaValue> | undefined
): SemaMap {
	if (!overrides || Object.keys(overrides).length === 0) return baseMap;
	let next: unknown = baseMap;
	for (const [path, delta] of Object.entries(overrides)) {
		next = applyPathOverride(next, path.split('.'), delta);
	}
	return next as unknown as SemaMap;
}

function applyPathOverride(root: unknown, parts: string[], delta: DeltaValue): unknown {
	if (parts.length === 0) return applyLeaf(root, delta, 'replace');
	const next = cloneContainer(root);
	let cursor = next;
	let sourceCursor = root;

	for (let i = 0; i < parts.length - 1; i++) {
		const key = parts[i];
		const sourceChild = readChild(sourceCursor, key);
		const child = cloneContainer(sourceChild);
		cursor[key] = child;
		cursor = child;
		sourceCursor = sourceChild;
	}

	const leafKey = parts[parts.length - 1];
	// Runtime path overrides REPLACE primitive leaves (designer setting
	// `'families.commit.base.sound.pitch': 850` means SET to 850, not
	// add). Use `{ op: 'add' }` if explicit additive semantics are needed.
	cursor[leafKey] = applyLeaf(readChild(sourceCursor, leafKey), delta, 'replace');
	return next;
}

function cloneContainer(value: unknown): Record<string, unknown> {
	if (Array.isArray(value)) return [...value] as unknown as Record<string, unknown>;
	if (isRecord(value)) return { ...value };
	return {};
}

function readChild(value: unknown, key: string): unknown {
	if (!isRecord(value) && !Array.isArray(value)) return undefined;
	return (value as Record<string, unknown>)[key];
}