package blob

import (
	"bytes"
	"os"
	"strings"
	"testing"
)

func testStore(t *testing.T) *Store {
	t.Helper()
	return NewStore(t.TempDir())
}

func TestWriteAndRead(t *testing.T) {
	s := testStore(t)
	data := []byte("hello, exocortex")

	id, err := s.Write(data)
	if err != nil {
		t.Fatalf("Write failed: %v", err)
	}
	if id == "" {
		t.Fatal("Write returned empty ID")
	}

	got, err := s.Read(id)
	if err != nil {
		t.Fatalf("Read failed: %v", err)
	}
	if !bytes.Equal(got, data) {
		t.Fatalf("data mismatch: got %q, want %q", got, data)
	}
}

func TestWriteDeterministic(t *testing.T) {
	s := testStore(t)
	data := []byte("deterministic content")

	id1, err := s.Write(data)
	if err != nil {
		t.Fatalf("first Write failed: %v", err)
	}

	id2, err := s.Write(data)
	if err != nil {
		t.Fatalf("second Write failed: %v", err)
	}

	if id1 != id2 {
		t.Fatalf("same content should produce same ID: %q vs %q", id1, id2)
	}
}

func TestExists(t *testing.T) {
	s := testStore(t)
	data := []byte("existence check")

	if s.Exists("nonexistent") {
		t.Fatal("Exists should return false for missing blob")
	}

	id, err := s.Write(data)
	if err != nil {
		t.Fatalf("Write failed: %v", err)
	}

	if !s.Exists(id) {
		t.Fatal("Exists should return true after write")
	}
}

func TestReadMissing(t *testing.T) {
	s := testStore(t)
	_, err := s.Read("0000000000000000000000000000000000000000000000000000000000000000")
	if err == nil {
		t.Fatal("Read of missing blob should return error")
	}
}

func TestPathLayout(t *testing.T) {
	s := NewStore("/base")
	// A 64-char hex SHA256 hash split into 4-char segments.
	id := "a1b2c3d4e5f67890a1b2c3d4e5f67890a1b2c3d4e5f67890a1b2c3d4e5f67890"
	p := s.Path(id)

	// Should contain the 4-char directory segments.
	if !strings.Contains(p, "a1b2") {
		t.Fatalf("path should contain 4-char segments: %q", p)
	}
	if !strings.HasSuffix(p, id) {
		t.Fatalf("path should end with the full hash: %q", p)
	}
}

func TestHashData(t *testing.T) {
	data := []byte("hash me")
	h := HashData(data)
	if len(h) != 64 {
		t.Fatalf("expected 64-char hex hash, got %d chars", len(h))
	}

	// Same data should produce same hash.
	h2 := HashData(data)
	if h != h2 {
		t.Fatal("HashData is not deterministic")
	}
}

func TestWriteLargeBlob(t *testing.T) {
	s := testStore(t)
	data := make([]byte, 1<<20) // 1 MiB
	for i := range data {
		data[i] = byte(i % 256)
	}

	id, err := s.Write(data)
	if err != nil {
		t.Fatalf("Write failed: %v", err)
	}

	got, err := s.Read(id)
	if err != nil {
		t.Fatalf("Read failed: %v", err)
	}

	if !bytes.Equal(got, data) {
		t.Fatal("large blob round-trip failed")
	}
}

func TestWriteCreatesDirectories(t *testing.T) {
	s := testStore(t)
	data := []byte("directory creation test")

	id, err := s.Write(data)
	if err != nil {
		t.Fatalf("Write failed: %v", err)
	}

	p := s.Path(id)
	if _, err := os.Stat(p); err != nil {
		t.Fatalf("blob file should exist at %q: %v", p, err)
	}
}