package deltacomp

import (
	"bytes"
	"encoding/hex"
	"fmt"
	"os"
	"testing"

	"erupe-ce/server/channelserver/compression/nullcomp"
)

var tests = []struct {
	before  string
	patches []string
	after   string
}{
	{
		"hunternavi_0_before.bin",
		[]string{
			"hunternavi_0_patch_0.bin",
			"hunternavi_0_patch_1.bin",
		},
		"hunternavi_0_after.bin",
	},
	{
		// From "Character Progression 1 Creation-NPCs-Tours"
		"hunternavi_1_before.bin",
		[]string{
			"hunternavi_1_patch_0.bin",
			"hunternavi_1_patch_1.bin",
			"hunternavi_1_patch_2.bin",
			"hunternavi_1_patch_3.bin",
			"hunternavi_1_patch_4.bin",
			"hunternavi_1_patch_5.bin",
			"hunternavi_1_patch_6.bin",
			"hunternavi_1_patch_7.bin",
			"hunternavi_1_patch_8.bin",
			"hunternavi_1_patch_9.bin",
			"hunternavi_1_patch_10.bin",
			"hunternavi_1_patch_11.bin",
			"hunternavi_1_patch_12.bin",
			"hunternavi_1_patch_13.bin",
			"hunternavi_1_patch_14.bin",
			"hunternavi_1_patch_15.bin",
			"hunternavi_1_patch_16.bin",
			"hunternavi_1_patch_17.bin",
			"hunternavi_1_patch_18.bin",
			"hunternavi_1_patch_19.bin",
			"hunternavi_1_patch_20.bin",
			"hunternavi_1_patch_21.bin",
			"hunternavi_1_patch_22.bin",
			"hunternavi_1_patch_23.bin",
			"hunternavi_1_patch_24.bin",
		},
		"hunternavi_1_after.bin",
	},
	{
		// From "Progress Gogo GRP Grind 9 and Armor Upgrades and Partner Equip and Lost Cat and Manager talk and Pugi Order"
		// Not really sure this one counts as a valid test as the input and output are exactly the same. The patches cancel each other out.
		"platedata_0_before.bin",
		[]string{
			"platedata_0_patch_0.bin",
			"platedata_0_patch_1.bin",
		},
		"platedata_0_after.bin",
	},
}

func readTestDataFile(filename string) []byte {
	data, err := os.ReadFile(fmt.Sprintf("./test_data/%s", filename))
	if err != nil {
		panic(err)
	}
	return data
}

func TestDeltaPatch(t *testing.T) {
	for k, tt := range tests {
		testname := fmt.Sprintf("delta_patch_test_%d", k)
		t.Run(testname, func(t *testing.T) {
			// Load the test binary data.
			beforeData, err := nullcomp.Decompress(readTestDataFile(tt.before))
			if err != nil {
				t.Error(err)
			}

			var patches [][]byte
			for _, patchName := range tt.patches {
				patchData := readTestDataFile(patchName)
				patches = append(patches, patchData)
			}

			afterData, err := nullcomp.Decompress(readTestDataFile(tt.after))
			if err != nil {
				t.Error(err)
			}

			// Now actually test calling ApplyDataDiff.
			data := beforeData

			// Apply the patches in order.
			for i, patch := range patches {
				fmt.Println("patch index: ", i)
				data = ApplyDataDiff(patch, data)
			}

			if !bytes.Equal(data, afterData) {
				t.Errorf("got out\n\t%s\nwant\n\t%s", hex.Dump(data), hex.Dump(afterData))
			}
		})
	}
}

func TestApplyDataDiffEmptyDiff(t *testing.T) {
	baseData := []byte{1, 2, 3, 4, 5}
	diff := []byte{}

	result := ApplyDataDiff(diff, baseData)
	if !bytes.Equal(result, baseData) {
		t.Errorf("ApplyDataDiff with empty diff should return base data")
	}
}

func TestApplyDataDiffEmptyBase(t *testing.T) {
	baseData := []byte{}
	diff := []byte{}

	result := ApplyDataDiff(diff, baseData)
	if len(result) != 0 {
		t.Errorf("ApplyDataDiff with empty base and diff should return empty")
	}
}

func TestCheckReadUint8Error(t *testing.T) {
	r := bytes.NewReader([]byte{})
	_, err := checkReadUint8(r)
	if err == nil {
		t.Error("checkReadUint8 on empty reader should return error")
	}
}

func TestCheckReadUint16Error(t *testing.T) {
	r := bytes.NewReader([]byte{0x01}) // Only 1 byte, need 2
	_, err := checkReadUint16(r)
	if err == nil {
		t.Error("checkReadUint16 with insufficient data should return error")
	}
}

func TestCheckReadUint16Success(t *testing.T) {
	r := bytes.NewReader([]byte{0x12, 0x34})
	val, err := checkReadUint16(r)
	if err != nil {
		t.Errorf("checkReadUint16 error = %v", err)
	}
	if val != 0x1234 {
		t.Errorf("checkReadUint16 = 0x%04X, want 0x1234", val)
	}
}

func TestReadCountError(t *testing.T) {
	r := bytes.NewReader([]byte{})
	_, err := readCount(r)
	if err == nil {
		t.Error("readCount on empty reader should return error")
	}
}

func TestReadCountExtended(t *testing.T) {
	// When count8 is 0, read count16
	r := bytes.NewReader([]byte{0x00, 0x01, 0x00}) // count8=0, count16=256
	count, err := readCount(r)
	if err != nil {
		t.Errorf("readCount error = %v", err)
	}
	if count != 256 {
		t.Errorf("readCount = %d, want 256", count)
	}
}

func TestReadCountExtendedError(t *testing.T) {
	// count8 is 0 but not enough bytes for count16
	r := bytes.NewReader([]byte{0x00, 0x01})
	_, err := readCount(r)
	if err == nil {
		t.Error("readCount with insufficient data for count16 should return error")
	}
}

func TestCheckReadUint16EmptyReader(t *testing.T) {
	r := bytes.NewReader([]byte{})
	_, err := checkReadUint16(r)
	if err == nil {
		t.Error("checkReadUint16 on empty reader should return error")
	}
}