import { HttpParams, HttpParameterCodec } from '@angular/common/http';
import { CustomHttpParameterCodec, IdentityHttpParameterCodec } from './encoder';

export enum QueryParamStyle {
	Json,
	Form,
	DeepObject,
	SpaceDelimited,
	PipeDelimited
}

export type Delimiter = ',' | ' ' | '|' | '\t';

export interface ParamOptions {
	/** When true, serialized as multiple repeated key=value pairs. When false, serialized as a single key with joined values using `delimiter`. */
	explode?: boolean;
	/** Delimiter used when explode=false. The delimiter itself is inserted unencoded between encoded values. */
	delimiter?: Delimiter;
}

interface ParamEntry {
	values: string[];
	options: Required<ParamOptions>;
}

export class OpenApiHttpParams {
	private params: Map<string, ParamEntry> = new Map();
	private defaults: Required<ParamOptions>;
	private encoder: HttpParameterCodec;

	/**
	 * @param encoder  Parameter serializer
	 * @param defaults Global defaults used when a specific parameter has no explicit options.
	 *                 By OpenAPI default, explode is true for query params with style=form.
	 */
	constructor(encoder?: HttpParameterCodec, defaults?: { explode?: boolean; delimiter?: Delimiter }) {
		this.encoder = encoder || new CustomHttpParameterCodec();
		this.defaults = {
			explode: defaults?.explode ?? true,
			delimiter: defaults?.delimiter ?? ','
		};
	}

	private resolveOptions(local?: ParamOptions): Required<ParamOptions> {
		return {
			explode: local?.explode ?? this.defaults.explode,
			delimiter: local?.delimiter ?? this.defaults.delimiter
		};
	}

	/**
	 * Replace the parameter's values and (optionally) its options.
	 * Options are stored per-parameter (not global).
	 */
	set(key: string, values: string[] | string, options?: ParamOptions): this {
		const arr = Array.isArray(values) ? values.slice() : [values];
		const opts = this.resolveOptions(options);
		this.params.set(key, { values: arr, options: opts });
		return this;
	}

	/**
	 * Append a single value to the parameter. If the parameter didn't exist it will be created
	 * and use resolved options (global defaults merged with any provided options).
	 */
	append(key: string, value: string, options?: ParamOptions): this {
		const entry = this.params.get(key);
		if (entry) {
			// If new options provided, override the stored options for subsequent serialization
			if (options) {
				entry.options = this.resolveOptions({ ...entry.options, ...options });
			}
			entry.values.push(value);
		} else {
			this.set(key, [value], options);
		}
		return this;
	}

	/**
	 * Serialize to a query string according to per-parameter OpenAPI options.
	 * - If explode=true for that parameter → repeated key=value pairs (each value encoded).
	 * - If explode=false for that parameter → single key=value where values are individually encoded
	 *   and joined using the configured delimiter. The delimiter character is inserted AS-IS
	 *   (not percent-encoded).
	 */
	toString(): string {
		const records = this.toRecord();
		const parts: string[] = [];

		for (const key in records) {
			parts.push(`${key}=${records[key]}`);
		}

		return parts.join('&');
	}

	/**
	 * Return parameters as a plain record.
	 * - If a parameter has exactly one value, returns that value directly.
	 * - If a parameter has multiple values, returns a readonly array of values.
	 */
	toRecord(): Record<string, string | number | boolean | ReadonlyArray<string | number | boolean>> {
		const parts: Record<string, string | number | boolean | ReadonlyArray<string | number | boolean>> = {};

		for (const [key, entry] of this.params.entries()) {
			const encodedKey = this.encoder.encodeKey(key);

			if (entry.options.explode) {
				parts[encodedKey] = entry.values.map((v) => this.encoder.encodeValue(v));
			} else {
				const encodedValues = entry.values.map((v) => this.encoder.encodeValue(v));

				// join with the delimiter *unencoded*
				parts[encodedKey] = encodedValues.join(entry.options.delimiter);
			}
		}

		return parts;
	}

	/**
	 * Return an Angular's HttpParams with an identity parameter codec as the parameters are already encoded.
	 */
	toHttpParams(): HttpParams {
		const records = this.toRecord();

		let httpParams = new HttpParams({ encoder: new IdentityHttpParameterCodec() });

		return httpParams.appendAll(records);
	}
}

export function concatHttpParamsObject(
	httpParams: OpenApiHttpParams,
	key: string,
	item: {
		[index: string]: any;
	},
	delimiter: Delimiter
): OpenApiHttpParams {
	let keyAndValues: string[] = [];

	for (const k in item) {
		keyAndValues.push(k);

		const value = item[k];

		if (Array.isArray(value)) {
			keyAndValues.push(...value.map(convertToString));
		} else {
			keyAndValues.push(convertToString(value));
		}
	}

	return httpParams.set(key, keyAndValues, { explode: false, delimiter: delimiter });
}

function convertToString(value: any): string {
	if (value instanceof Date) {
		return value.toISOString();
	} else {
		return value.toString();
	}
}