package imgcache

import (
	"bytes"
	"io"
	"os"
	"path/filepath"
	"testing"

	"sneak.berlin/go/pixa/internal/imagerequest"
)

// TestStoreSource_StoresIdenticalBytesOfTwoURLsTwice stores the same bytes
// for two source URLs and checks that each URL has a source_content row of
// its own and a file of its own, named by its source key under
// cache/sources/<ab>/<cd>/.
func TestStoreSource_StoresIdenticalBytesOfTwoURLsTwice(t *testing.T) {
	t.Parallel()

	cache, stateDir := newEvictionTestCache(t, 1<<30)
	content := bytes.Repeat([]byte{0x5A}, 400)

	keys := map[string]imagerequest.SourceKey{
		"/a.jpg": storeEvictionTestSource(t, cache, testHostCDN, "/a.jpg", content),
		"/b.jpg": storeEvictionTestSource(t, cache, testHostCDN, "/b.jpg", content),
	}
	t.Logf("source keys: %v", keys)

	if keys["/a.jpg"] == keys["/b.jpg"] {
		t.Fatalf("both source URLs got the key %s", keys["/a.jpg"])
	}

	for sourcePath, key := range keys {
		rows := countRows(t, cache,
			`SELECT COUNT(*) FROM source_content WHERE source_key = ?`, string(key))
		if rows != 1 {
			t.Errorf("%s has %d source_content rows, want 1", sourcePath, rows)
		}

		name := string(key)
		file := filepath.Join(stateDir, "cache", "sources", name[0:2], name[2:4], name)

		stored, err := os.ReadFile(file) //nolint:gosec // path in the test's state dir
		if err != nil || !bytes.Equal(stored, content) {
			t.Errorf("file of %s at %s holds %d bytes (error %v), want the %d stored",
				sourcePath, file, len(stored), err, len(content))
		}
	}

	usage, err := cache.UsageBytes(t.Context())
	if err != nil {
		t.Fatalf("UsageBytes() error = %v", err)
	}

	if usage != 800 {
		t.Errorf("UsageBytes() = %d, want 800, the 400 bytes once for each URL", usage)
	}
}

// TestEvictSourceBlob_LeavesSourceWithIdenticalBytesServed stores the same
// bytes for two source URLs and evicts the first. Its row and file must be
// gone, and the second must still be found and read from the cache.
func TestEvictSourceBlob_LeavesSourceWithIdenticalBytesServed(t *testing.T) {
	t.Parallel()

	cache, _ := newEvictionTestCache(t, 1<<30)
	content := bytes.Repeat([]byte{0x5B}, 400)

	evicted := storeEvictionTestSource(t, cache, testHostCDN, "/evicted.jpg", content)
	storeEvictionTestSource(t, cache, testHostCDN, "/kept.jpg", content)

	err := cache.evictSourceBlob(t.Context(), evicted)
	if err != nil {
		t.Fatalf("evictSourceBlob() error = %v", err)
	}

	if cache.srcContent.Exists(evicted) {
		t.Error("the evicted source's file is still on disk")
	}

	if n := countRows(t, cache,
		`SELECT COUNT(*) FROM source_content WHERE source_key = ?`, string(evicted),
	); n != 0 {
		t.Errorf("the evicted source still has %d source_content rows", n)
	}

	kept, err := cache.LookupSource(t.Context(), &imagerequest.Request{
		Source: imagerequest.Source{Host: testHostCDN, Path: "/kept.jpg"},
	})
	t.Logf("LookupSource() of the kept source = %q, error %v", kept, err)

	if err != nil || kept == "" {
		t.Fatalf("LookupSource() of the kept source = %q, %v; want it cached", kept, err)
	}

	reader, _, err := cache.GetSourceContent(kept)
	if err != nil {
		t.Fatalf("GetSourceContent() of the kept source error = %v", err)
	}

	defer func() { _ = reader.Close() }()

	served, err := io.ReadAll(reader)
	if err != nil {
		t.Fatalf("reading the kept source: %v", err)
	}

	if !bytes.Equal(served, content) {
		t.Errorf("the kept source reads as %d bytes, want the %d stored",
			len(served), len(content))
	}
}

// TestStoreSource_FailedRowWriteLeavesNoFile drops source_content, so that
// StoreSource cannot write the source's row, and checks that the store fails
// and leaves no file under the source's key.
func TestStoreSource_FailedRowWriteLeavesNoFile(t *testing.T) {
	t.Parallel()

	cache, _ := newEvictionTestCache(t, 1<<30)

	_, err := cache.db.ExecContext(t.Context(), `DROP TABLE source_content`)
	if err != nil {
		t.Fatalf("failed to drop source_content: %v", err)
	}

	req := &imagerequest.Request{
		Source: imagerequest.Source{Host: testHostCDN, Path: testPathCat},
	}
	key, err := cache.StoreSource(t.Context(), req,
		bytes.NewReader([]byte("source bytes")))
	t.Logf("StoreSource() = %q, error = %v", key, err)

	if err == nil {
		t.Error("StoreSource() error = nil, want the failed row write")
	}

	if cache.srcContent.Exists(req.Source.Key()) {
		t.Error("the source's file is on disk although its row was not written")
	}
}