import { NextResponse } from "next/server"
import { fetchQuery } from "convex/nextjs"
import { api } from "@/convex/_generated/api"
import { hasConvexUrl } from "@/lib/convex-config"
import {
  filterTrustedEbayListings,
  rankListingsForQuery,
  type CachedEbayListing,
  type EbayCacheState,
} from "@/lib/ebay-parts-match"

type CacheSource = "convex" | "fallback"

function getDisabledCacheState(message: string): EbayCacheState {
  return {
    key: "manual-parts",
    status: "disabled",
    lastSuccessfulAt: null,
    lastAttemptAt: null,
    nextEligibleAt: null,
    lastError: message,
    consecutiveFailures: 0,
    queryCount: 0,
    itemCount: 0,
    sourceQueries: [],
    freshnessMs: null,
    isStale: true,
    listingCount: 0,
    activeListingCount: 0,
    message,
  }
}

function getErrorCacheState(message: string): EbayCacheState {
  const now = Date.now()
  return {
    key: "manual-parts",
    status: "error",
    lastSuccessfulAt: null,
    lastAttemptAt: now,
    nextEligibleAt: null,
    lastError: message,
    consecutiveFailures: 1,
    queryCount: 0,
    itemCount: 0,
    sourceQueries: [],
    freshnessMs: null,
    isStale: true,
    listingCount: 0,
    activeListingCount: 0,
    message,
  }
}

export async function GET(request: Request) {
  const { searchParams } = new URL(request.url)
  const keywords = searchParams.get("keywords")?.trim() || ""
  const maxResults = Math.min(
    Math.max(Number.parseInt(searchParams.get("maxResults") || "6", 10) || 6, 1),
    20
  )

  if (!keywords) {
    return NextResponse.json(
      { error: "Keywords parameter is required" },
      { status: 400 }
    )
  }

  if (!hasConvexUrl()) {
    const message =
      "Cached eBay backend is disabled because NEXT_PUBLIC_CONVEX_URL is not configured."
    return NextResponse.json({
      query: keywords,
      results: [],
      cache: getDisabledCacheState(message),
      cacheSource: "fallback" satisfies CacheSource,
      error: message,
    })
  }

  try {
    const [overview, listings] = await Promise.all([
      fetchQuery(api.ebay.getCacheOverview, {}),
      fetchQuery(api.ebay.listCachedListings, { limit: 200 }),
    ])

    const trustedListings = filterTrustedEbayListings(
      listings as CachedEbayListing[]
    )
    const ranked = rankListingsForQuery(
      keywords,
      trustedListings,
      maxResults
    )

    return NextResponse.json({
      query: keywords,
      results: ranked,
      cache: overview,
      cacheSource: "convex" satisfies CacheSource,
    })
  } catch (error) {
    console.error("Failed to load cached eBay listings:", error)
    const message =
      error instanceof Error
        ? `Cached eBay listings are unavailable: ${error.message}`
        : "Cached eBay listings are unavailable."
    return NextResponse.json(
      {
        query: keywords,
        results: [],
        cache: getErrorCacheState(message),
        cacheSource: "fallback" satisfies CacheSource,
        error: message,
      },
      { status: 200 }
    )
  }
}