import { useState } from 'react'
import { AlertCircle, ChevronDown, ChevronRight, X } from 'lucide-react'
import type { GenerationError } from '../lib/generation-errors'

interface GenerationErrorDialogProps {
  error: GenerationError
  onDismiss: () => void
}

function assertNever(value: never): never {
  throw new Error(`Unexpected generation error variant: ${JSON.stringify(value)}`)
}

function getGenericHumanMessage(message: string): string {
  const lower = message.toLowerCase()
  if (lower.includes('409') || lower.includes('already')) {
    return 'A generation is already in progress. Please wait for it to finish or cancel it.'
  }
  if (lower.includes('cuda') || lower.includes('out of memory') || lower.includes('oom')) {
    return 'The GPU ran out of memory. Try a lower resolution or shorter duration.'
  }
  if ((lower.includes('model') && (lower.includes('not found') || lower.includes('load')))) {
    return 'The AI model failed to load. Please check your setup and try again.'
  }
  if (lower.includes('fetch') || lower.includes('network') || lower.includes('econnrefused')) {
    return 'Could not connect to the generation server. Make sure the backend is running.'
  }
  if (lower.includes('input image') || lower.includes('canvas') || lower.includes('cors')) {
    return 'Failed to prepare the input image. The file may be corrupted or inaccessible.'
  }
  if (lower.includes('could not auto-generate') || lower.includes('send to genspace')) {
    return message
  }
  return 'Something went wrong during generation. Please try again.'
}

function getDialogModel(error: GenerationError): {
  humanMessage: string
  technicalDetails: string
  primaryAction?: {
    label: string
    onClick: () => void
  }
} {
  switch (error.status) {
    case 402:
      switch (error.error.code) {
        case 'LTX_INSUFFICIENT_FUNDS':
          return {
            humanMessage: 'Your LTX API credits are insufficient for this generation. Buy more credits in LTX and try again.',
            technicalDetails: JSON.stringify(error.error, null, 2),
            primaryAction: {
              label: 'Buy Credits',
              onClick: () => {
                void window.electronAPI.openLtxBillingPage()
              },
            },
          }
      }
      return assertNever(error.error.code)
    case '4XX':
    case '5XX':
    case 'default':
      return {
        humanMessage: getGenericHumanMessage(error.error.message),
        technicalDetails: JSON.stringify(error.error, null, 2),
      }
    default:
      return assertNever(error)
  }
}

export function GenerationErrorDialog({ error, onDismiss }: GenerationErrorDialogProps) {
  const [detailsExpanded, setDetailsExpanded] = useState(false)
  const dialogModel = getDialogModel(error)

  return (
    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/70 backdrop-blur-sm">
      <div className="bg-zinc-900 border border-zinc-700 rounded-xl shadow-2xl w-[480px] flex flex-col overflow-hidden">
        <div className="flex items-center justify-between px-6 py-4 border-b border-zinc-800">
          <div className="flex items-center gap-3">
            <AlertCircle className="h-5 w-5 text-red-400" />
            <h2 className="text-base font-semibold text-zinc-100">Generation Failed</h2>
          </div>
          <button
            onClick={onDismiss}
            className="p-1.5 rounded-lg hover:bg-zinc-800 text-zinc-500 hover:text-zinc-300 transition-colors"
          >
            <X className="h-4 w-4" />
          </button>
        </div>

        <div className="px-6 py-5">
          <p className="text-sm text-zinc-300 leading-relaxed">
            {dialogModel.humanMessage}
          </p>

          <div className="mt-4">
            <button
              onClick={() => setDetailsExpanded(!detailsExpanded)}
              className="flex items-center gap-2 text-xs font-semibold text-zinc-400 uppercase tracking-wider hover:text-zinc-300"
            >
              {detailsExpanded ? <ChevronDown className="h-3.5 w-3.5" /> : <ChevronRight className="h-3.5 w-3.5" />}
              Technical Details
            </button>
            {detailsExpanded && (
              <pre className="mt-2 bg-zinc-800/50 rounded-lg p-3 text-[11px] text-zinc-400 whitespace-pre-wrap break-words max-h-40 overflow-auto">
                {dialogModel.technicalDetails}
              </pre>
            )}
          </div>
        </div>

        <div className={`px-6 py-4 border-t border-zinc-800 flex items-center gap-3 ${dialogModel.primaryAction ? 'justify-between' : 'justify-end'}`}>
          {dialogModel.primaryAction ? (
            <button
              onClick={onDismiss}
              className="px-4 py-2 bg-zinc-800 text-zinc-100 text-sm font-medium rounded-lg hover:bg-zinc-700 transition-colors"
            >
              Try Again
            </button>
          ) : null}
          {dialogModel.primaryAction ? (
            <button
              onClick={dialogModel.primaryAction.onClick}
              className="px-4 py-2 bg-zinc-100 text-zinc-900 text-sm font-medium rounded-lg hover:bg-white transition-colors"
            >
              {dialogModel.primaryAction.label}
            </button>
          ) : (
            <button
              onClick={onDismiss}
              className="px-4 py-2 bg-zinc-100 text-zinc-900 text-sm font-medium rounded-lg hover:bg-white transition-colors"
            >
              Try Again
            </button>
          )}
        </div>
      </div>
    </div>
  )
}