import type { MaterialSourceLocation } from './material-preprocess.js';

/**
 * Source metadata for material declaration callsite.
 */
export interface MaterialSourceMetadata {
	component?: string;
	file?: string;
	line?: number;
	column?: number;
	functionName?: string;
}

export interface ComputeSourceLocation {
	kind: 'compute';
	line: number;
}

export type ShaderSourceLocation = MaterialSourceLocation | ComputeSourceLocation;

/**
 * One WGSL compiler diagnostic enriched with source-location metadata.
 */
export interface ShaderCompilationDiagnostic {
	generatedLine: number;
	message: string;
	linePos?: number;
	lineLength?: number;
	sourceLocation: ShaderSourceLocation | null;
}

/**
 * Runtime context snapshot captured for shader compilation diagnostics.
 */
export interface ShaderCompilationRuntimeContext {
	materialSignature?: string;
	passGraph?: {
		passCount: number;
		enabledPassCount: number;
		inputs: string[];
		outputs: string[];
	};
	activeRenderTargets: string[];
}

/**
 * Structured payload attached to WGSL compilation errors.
 */
export interface ShaderCompilationDiagnosticsPayload {
	kind: 'shader-compilation';
	shaderStage?: 'fragment' | 'compute';
	diagnostics: ShaderCompilationDiagnostic[];
	fragmentSource: string;
	computeSource?: string;
	includeSources: Record<string, string>;
	defineBlockSource?: string;
	materialSource: MaterialSourceMetadata | null;
	runtimeContext?: ShaderCompilationRuntimeContext;
}

type MotionGPUErrorWithDiagnostics = Error & {
	motiongpuDiagnostics?: unknown;
};

function isMaterialSourceMetadata(value: unknown): value is MaterialSourceMetadata {
	if (value === null || typeof value !== 'object') {
		return false;
	}

	const record = value as Record<string, unknown>;
	if (record.component !== undefined && typeof record.component !== 'string') {
		return false;
	}
	if (record.file !== undefined && typeof record.file !== 'string') {
		return false;
	}
	if (record.functionName !== undefined && typeof record.functionName !== 'string') {
		return false;
	}
	if (record.line !== undefined && typeof record.line !== 'number') {
		return false;
	}
	if (record.column !== undefined && typeof record.column !== 'number') {
		return false;
	}

	return true;
}

function isShaderSourceLocation(value: unknown): value is ShaderSourceLocation | null {
	if (value === null) {
		return true;
	}

	if (typeof value !== 'object') {
		return false;
	}

	const record = value as Record<string, unknown>;
	const kind = record.kind;
	if (kind !== 'fragment' && kind !== 'include' && kind !== 'define' && kind !== 'compute') {
		return false;
	}

	return typeof record.line === 'number';
}

function isShaderCompilationDiagnostic(value: unknown): value is ShaderCompilationDiagnostic {
	if (value === null || typeof value !== 'object') {
		return false;
	}

	const record = value as Record<string, unknown>;
	if (typeof record.generatedLine !== 'number') {
		return false;
	}
	if (typeof record.message !== 'string') {
		return false;
	}
	if (record.linePos !== undefined && typeof record.linePos !== 'number') {
		return false;
	}
	if (record.lineLength !== undefined && typeof record.lineLength !== 'number') {
		return false;
	}
	if (!isShaderSourceLocation(record.sourceLocation)) {
		return false;
	}

	return true;
}

function isStringArray(value: unknown): value is string[] {
	return Array.isArray(value) && value.every((entry) => typeof entry === 'string');
}

function isShaderCompilationRuntimeContext(
	value: unknown
): value is ShaderCompilationRuntimeContext {
	if (value === null || typeof value !== 'object') {
		return false;
	}

	const record = value as Record<string, unknown>;
	if (record.materialSignature !== undefined && typeof record.materialSignature !== 'string') {
		return false;
	}
	if (!isStringArray(record.activeRenderTargets)) {
		return false;
	}
	const passGraph = record.passGraph;
	if (passGraph === undefined) {
		return true;
	}
	if (passGraph === null || typeof passGraph !== 'object') {
		return false;
	}

	const passGraphRecord = passGraph as Record<string, unknown>;
	if (typeof passGraphRecord.passCount !== 'number') {
		return false;
	}
	if (typeof passGraphRecord.enabledPassCount !== 'number') {
		return false;
	}
	if (!isStringArray(passGraphRecord.inputs) || !isStringArray(passGraphRecord.outputs)) {
		return false;
	}

	return true;
}

/**
 * Attaches structured diagnostics payload to an Error.
 */
export function attachShaderCompilationDiagnostics(
	error: Error,
	payload: ShaderCompilationDiagnosticsPayload
): Error {
	(error as MotionGPUErrorWithDiagnostics).motiongpuDiagnostics = payload;
	return error;
}

/**
 * Extracts structured diagnostics payload from unknown error value.
 */
export function getShaderCompilationDiagnostics(
	error: unknown
): ShaderCompilationDiagnosticsPayload | null {
	if (!(error instanceof Error)) {
		return null;
	}

	const payload = (error as MotionGPUErrorWithDiagnostics).motiongpuDiagnostics;
	if (payload === null || typeof payload !== 'object') {
		return null;
	}

	const record = payload as Record<string, unknown>;
	if (record.kind !== 'shader-compilation') {
		return null;
	}
	if (
		record.shaderStage !== undefined &&
		record.shaderStage !== 'fragment' &&
		record.shaderStage !== 'compute'
	) {
		return null;
	}
	if (
		!Array.isArray(record.diagnostics) ||
		!record.diagnostics.every(isShaderCompilationDiagnostic)
	) {
		return null;
	}
	if (typeof record.fragmentSource !== 'string') {
		return null;
	}
	if (record.computeSource !== undefined && typeof record.computeSource !== 'string') {
		return null;
	}
	if (record.defineBlockSource !== undefined && typeof record.defineBlockSource !== 'string') {
		return null;
	}
	if (record.includeSources === null || typeof record.includeSources !== 'object') {
		return null;
	}
	const includeSources = record.includeSources as Record<string, unknown>;
	if (Object.values(includeSources).some((value) => typeof value !== 'string')) {
		return null;
	}
	if (record.materialSource !== null && !isMaterialSourceMetadata(record.materialSource)) {
		return null;
	}
	if (
		record.runtimeContext !== undefined &&
		!isShaderCompilationRuntimeContext(record.runtimeContext)
	) {
		return null;
	}

	return {
		kind: 'shader-compilation',
		...(record.shaderStage !== undefined
			? { shaderStage: record.shaderStage as 'fragment' | 'compute' }
			: {}),
		diagnostics: record.diagnostics as ShaderCompilationDiagnostic[],
		fragmentSource: record.fragmentSource,
		...(record.computeSource !== undefined
			? { computeSource: record.computeSource as string }
			: {}),
		includeSources: includeSources as Record<string, string>,
		...(record.defineBlockSource !== undefined
			? { defineBlockSource: record.defineBlockSource as string }
			: {}),
		materialSource: (record.materialSource ?? null) as MaterialSourceMetadata | null,
		...(record.runtimeContext !== undefined
			? { runtimeContext: record.runtimeContext as ShaderCompilationRuntimeContext }
			: {})
	};
}