/**
 * Route param validation for One routes.
 *
 * Provides type-safe route parameter validation with support for
 * Zod, Valibot, and custom validation functions. Runs before navigation
 * to catch invalid routes early.
 */

import type { StandardSchema, ZodLikeSchema, SearchValidatorFn } from './validateSearch'

/**
 * All supported validator types for route params
 */
export type ParamValidator<TInput = Record<string, unknown>, TOutput = TInput> =
  | StandardSchema<TInput, TOutput>
  | ZodLikeSchema<TOutput>
  | SearchValidatorFn<TInput, TOutput>

/**
 * Infer the output type from a param validator
 */
export type InferParamOutput<T> =
  T extends StandardSchema<any, infer O>
    ? O
    : T extends ZodLikeSchema<infer O>
      ? O
      : T extends SearchValidatorFn<any, infer O>
        ? O
        : never

/**
 * Infer the input type from a param validator
 */
export type InferParamInput<T> =
  T extends StandardSchema<infer I, any>
    ? I
    : T extends ZodLikeSchema<any>
      ? Record<string, unknown>
      : T extends SearchValidatorFn<infer I, any>
        ? I
        : never

/**
 * Error thrown when route param validation fails
 */
export class ParamValidationError extends Error {
  readonly routerCode = 'VALIDATE_PARAMS'
  readonly issues: unknown[]
  readonly params: Record<string, unknown>

  constructor(message: string, params: Record<string, unknown>, issues: unknown[] = []) {
    super(message)
    this.name = 'ParamValidationError'
    this.params = params
    this.issues = issues
  }
}

/**
 * Error thrown when async route validation fails
 */
export class RouteValidationError extends Error {
  readonly routerCode = 'VALIDATE_ROUTE'
  readonly details?: Record<string, unknown>

  constructor(message: string, details?: Record<string, unknown>) {
    super(message)
    this.name = 'RouteValidationError'
    this.details = details
  }
}

/**
 * Props passed to validateRoute function
 */
export type ValidateRouteProps = {
  params: Record<string, string | string[]>
  search: Record<string, string | string[]>
  pathname: string
  href: string
}

/**
 * Result from validateRoute function
 */
export type ValidationResult =
  | { valid: true }
  | { valid: false; error: string; details?: Record<string, unknown> }

/**
 * Async route validation function type
 */
export type RouteValidationFn = (
  props: ValidateRouteProps
) => ValidationResult | Promise<ValidationResult> | void | Promise<void>

/**
 * Check if a value is a Standard Schema
 */
function isStandardSchema(value: unknown): value is StandardSchema {
  return (
    typeof value === 'object' &&
    value !== null &&
    '~standard' in value &&
    typeof (value as any)['~standard']?.validate === 'function'
  )
}

/**
 * Check if a value is a Zod-like schema
 */
function isZodLikeSchema(value: unknown): value is ZodLikeSchema {
  return (
    typeof value === 'object' &&
    value !== null &&
    typeof (value as any).parse === 'function'
  )
}

/**
 * Check if a value is a validator function
 */
function isValidatorFn(value: unknown): value is SearchValidatorFn<unknown, unknown> {
  return typeof value === 'function'
}

/**
 * Validate route params using the provided validator
 *
 * @param validator - The validator to use (Standard Schema, Zod-like, or function)
 * @param input - The raw route params to validate
 * @returns The validated and transformed params
 * @throws ParamValidationError if validation fails
 */
export function validateParams<T extends ParamValidator>(
  validator: T,
  input: Record<string, unknown>
): InferParamOutput<T> {
  if (isStandardSchema(validator)) {
    const result = validator['~standard'].validate(input)
    if (result.issues) {
      throw new ParamValidationError(
        'Route param validation failed',
        input,
        result.issues as unknown[]
      )
    }
    return result.value as InferParamOutput<T>
  }

  if (isZodLikeSchema(validator)) {
    if (validator.safeParse) {
      const result = validator.safeParse(input)
      if (!result.success) {
        throw new ParamValidationError('Route param validation failed', input, [
          result.error,
        ])
      }
      return result.data as InferParamOutput<T>
    }
    // Fallback to parse which throws on error
    try {
      return validator.parse(input) as InferParamOutput<T>
    } catch (error) {
      throw new ParamValidationError('Route param validation failed', input, [error])
    }
  }

  if (isValidatorFn(validator)) {
    try {
      return validator(input) as InferParamOutput<T>
    } catch (error) {
      throw new ParamValidationError('Route param validation failed', input, [error])
    }
  }

  throw new Error('Invalid validator provided to validateParams')
}

/**
 * Create a route param validator from a Zod schema.
 *
 * @example
 * ```ts
 * import { z } from 'zod'
 * import { zodParamValidator } from 'one'
 *
 * export const validateParams = zodParamValidator(z.object({
 *   id: z.string().uuid('Invalid ID format'),
 *   slug: z.string().min(1, 'Slug is required'),
 * }))
 * ```
 */
export function zodParamValidator<T extends ZodLikeSchema>(schema: T): T {
  return schema
}