package connector

import (
	"context"
	"crypto/md5"
	"encoding/hex"
	"errors"
	"io"
	"testing"
	"time"
)

// TestRSSConnectorOpenSyncFullAndIncremental verifies full and windowed sync.
func TestRSSConnectorOpenSyncFullAndIncremental(t *testing.T) {
	connector, err := NewRSSConnector(map[string]any{"feed_url": "https://example.com/feed.xml", "batch_size": 1})
	if err != nil {
		t.Fatalf("NewRSSConnector failed: %v", err)
	}
	connector.fetchFeed = staticRSSFeed

	fullSession, err := connector.OpenSync(context.Background(), SyncRequest{FromBeginning: true, WindowEnd: mustTime(t, "2026-01-05T00:00:00Z")})
	if err != nil {
		t.Fatalf("OpenSync full failed: %v", err)
	}
	first, err := fullSession.NextBatch(context.Background())
	if err != nil {
		t.Fatalf("NextBatch first failed: %v", err)
	}
	if len(first.Documents) != 1 || first.Documents[0].SourceID != expectedRSSSourceID("entry-old") {
		t.Fatalf("unexpected first full batch: %+v", first.Documents)
	}
	second, err := fullSession.NextBatch(context.Background())
	if err != nil {
		t.Fatalf("NextBatch second failed: %v", err)
	}
	if len(second.Documents) != 1 || second.Documents[0].SourceID != expectedRSSSourceID("entry-new") {
		t.Fatalf("unexpected second full batch: %+v", second.Documents)
	}
	if _, err = fullSession.NextBatch(context.Background()); !errors.Is(err, io.EOF) {
		t.Fatalf("NextBatch EOF = %v", err)
	}

	start := mustTime(t, "2026-01-02T00:00:00Z")
	incrementalSession, err := connector.OpenSync(context.Background(), SyncRequest{WindowStart: &start, WindowEnd: mustTime(t, "2026-01-04T00:00:00Z")})
	if err != nil {
		t.Fatalf("OpenSync incremental failed: %v", err)
	}
	batch, err := incrementalSession.NextBatch(context.Background())
	if err != nil {
		t.Fatalf("NextBatch incremental failed: %v", err)
	}
	if len(batch.Documents) != 1 {
		t.Fatalf("incremental batch len = %d, want 1", len(batch.Documents))
	}
	doc := batch.Documents[0]
	if doc.SourceID != expectedRSSSourceID("entry-new") {
		t.Fatalf("incremental source id = %s", doc.SourceID)
	}
	if doc.SemanticIdentifier != "New title" {
		t.Fatalf("semantic identifier = %q", doc.SemanticIdentifier)
	}
	if string(doc.Blob) != "New title\n\nNew body" {
		t.Fatalf("blob = %q", string(doc.Blob))
	}
	if doc.Metadata["link"] != "https://example.com/new" {
		t.Fatalf("link metadata = %v", doc.Metadata["link"])
	}
}

// TestRSSConnectorOpenPrune verifies complete slim snapshot generation.
func TestRSSConnectorOpenPrune(t *testing.T) {
	connector, err := NewRSSConnector(map[string]any{"feed_url": "https://example.com/feed.xml", "batch_size": 10})
	if err != nil {
		t.Fatalf("NewRSSConnector failed: %v", err)
	}
	connector.fetchFeed = staticRSSFeed
	session, err := connector.OpenPrune(context.Background(), PruneRequest{})
	if err != nil {
		t.Fatalf("OpenPrune failed: %v", err)
	}
	batch, err := session.NextBatch(context.Background())
	if err != nil {
		t.Fatalf("NextBatch failed: %v", err)
	}
	if len(batch.Documents) != 3 {
		t.Fatalf("prune snapshot len = %d, want 3", len(batch.Documents))
	}
	if batch.Documents[0].SourceID != expectedRSSSourceID("entry-old") ||
		batch.Documents[1].SourceID != expectedRSSSourceID("entry-new") ||
		batch.Documents[2].SourceID != expectedRSSSourceID("entry-future") {
		t.Fatalf("unexpected prune ids: %+v", batch.Documents)
	}
}

// staticRSSFeed returns a fixed RSS feed for tests.
func staticRSSFeed(ctx context.Context, feedURL string) ([]byte, error) {
	return []byte(`<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0">
  <channel>
    <title>Feed</title>
    <item>
      <guid>entry-old</guid>
      <title>Old title</title>
      <link>https://example.com/old</link>
      <pubDate>Thu, 01 Jan 2026 00:00:00 +0000</pubDate>
      <description><![CDATA[<p>Old body</p>]]></description>
    </item>
    <item>
      <guid>entry-new</guid>
      <title>New title</title>
      <link>https://example.com/new</link>
      <pubDate>Sat, 03 Jan 2026 00:00:00 +0000</pubDate>
      <description><![CDATA[<p>New body</p>]]></description>
      <category>news</category>
    </item>
    <item>
      <guid>entry-future</guid>
      <title>Future title</title>
      <link>https://example.com/future</link>
      <pubDate>Tue, 06 Jan 2026 00:00:00 +0000</pubDate>
      <description><![CDATA[<p>Future body</p>]]></description>
    </item>
  </channel>
</rss>`), nil
}

// expectedRSSSourceID returns Python-compatible RSS source ID.
func expectedRSSSourceID(value string) string {
	sum := md5.Sum([]byte(value))
	return "rss:" + hex.EncodeToString(sum[:])
}

// mustTime parses a test timestamp.
func mustTime(t *testing.T, value string) time.Time {
	t.Helper()
	parsed, err := time.Parse(time.RFC3339, value)
	if err != nil {
		t.Fatalf("parse time %q: %v", value, err)
	}
	return parsed
}