// Copyright 2024 Kelvin Clement Mwinuka
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package str_test

import (
	"errors"
	"fmt"
	"github.com/echovault/echovault/echovault"
	"github.com/echovault/echovault/internal"
	"github.com/echovault/echovault/internal/config"
	"github.com/echovault/echovault/internal/constants"
	"github.com/tidwall/resp"
	"net"
	"strconv"
	"strings"
	"sync"
	"testing"
)

var mockServer *echovault.EchoVault
var addr = "localhost"
var port int

func init() {
	port, _ = internal.GetFreePort()
	mockServer, _ = echovault.NewEchoVault(
		echovault.WithConfig(config.Config{
			BindAddr:       addr,
			Port:           uint16(port),
			DataDir:        "",
			EvictionPolicy: constants.NoEviction,
		}),
	)
	wg := sync.WaitGroup{}
	wg.Add(1)
	go func() {
		wg.Done()
		mockServer.Start()
	}()
	wg.Wait()
}

func Test_HandleSetRange(t *testing.T) {
	conn, err := net.Dial("tcp", fmt.Sprintf("%s:%d", addr, port))
	if err != nil {
		t.Error(err)
	}
	client := resp.NewConn(conn)

	tests := []struct {
		name             string
		key              string
		presetValue      string
		command          []string
		expectedValue    string
		expectedResponse int
		expectedError    error
	}{
		{
			name:             "Test that SETRANGE on non-existent string creates new string",
			key:              "SetRangeKey1",
			presetValue:      "",
			command:          []string{"SETRANGE", "SetRangeKey1", "10", "New String Value"},
			expectedValue:    "New String Value",
			expectedResponse: len("New String Value"),
			expectedError:    nil,
		},
		{
			name:             "Test SETRANGE with an offset that leads to a longer resulting string",
			key:              "SetRangeKey2",
			presetValue:      "Original String Value",
			command:          []string{"SETRANGE", "SetRangeKey2", "16", "Portion Replaced With This New String"},
			expectedValue:    "Original String Portion Replaced With This New String",
			expectedResponse: len("Original String Portion Replaced With This New String"),
			expectedError:    nil,
		},
		{
			name:             "SETRANGE with negative offset prepends the string",
			key:              "SetRangeKey3",
			presetValue:      "This is a preset value",
			command:          []string{"SETRANGE", "SetRangeKey3", "-10", "Prepended "},
			expectedValue:    "Prepended This is a preset value",
			expectedResponse: len("Prepended This is a preset value"),
			expectedError:    nil,
		},
		{
			name:             "SETRANGE with offset that embeds new string inside the old string",
			key:              "SetRangeKey4",
			presetValue:      "This is a preset value",
			command:          []string{"SETRANGE", "SetRangeKey4", "0", "That"},
			expectedValue:    "That is a preset value",
			expectedResponse: len("That is a preset value"),
			expectedError:    nil,
		},
		{
			name:             "SETRANGE with offset longer than original lengths appends the string",
			key:              "SetRangeKey5",
			presetValue:      "This is a preset value",
			command:          []string{"SETRANGE", "SetRangeKey5", "100", " Appended"},
			expectedValue:    "This is a preset value Appended",
			expectedResponse: len("This is a preset value Appended"),
			expectedError:    nil,
		},
		{
			name:             "SETRANGE with offset on the last character replaces last character with new string",
			key:              "SetRangeKey6",
			presetValue:      "This is a preset value",
			command:          []string{"SETRANGE", "SetRangeKey6", strconv.Itoa(len("This is a preset value") - 1), " replaced"},
			expectedValue:    "This is a preset valu replaced",
			expectedResponse: len("This is a preset valu replaced"),
			expectedError:    nil,
		},
		{
			name:             " Offset not integer",
			command:          []string{"SETRANGE", "key", "offset", "value"},
			expectedResponse: 0,
			expectedError:    errors.New("offset must be an integer"),
		},
		{
			name:             "SETRANGE target is not a string",
			key:              "test-int",
			presetValue:      "10",
			command:          []string{"SETRANGE", "test-int", "10", "value"},
			expectedResponse: 0,
			expectedError:    errors.New("value at key test-int is not a string"),
		},
		{
			name:             "Command too short",
			command:          []string{"SETRANGE", "key"},
			expectedResponse: 0,
			expectedError:    errors.New(constants.WrongArgsResponse),
		},
		{
			name:             "Command too long",
			command:          []string{"SETRANGE", "key", "offset", "value", "value1"},
			expectedResponse: 0,
			expectedError:    errors.New(constants.WrongArgsResponse),
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			if test.presetValue != "" {
				if err = client.WriteArray([]resp.Value{
					resp.StringValue("SET"),
					resp.StringValue(test.key),
					resp.StringValue(test.presetValue),
				}); err != nil {
					t.Error(err)
				}
				res, _, err := client.ReadValue()
				if err != nil {
					t.Error(err)
				}

				if !strings.EqualFold(res.String(), "ok") {
					t.Errorf("expected preset response to be OK, got %s", res.String())
				}
			}

			command := make([]resp.Value, len(test.command))
			for i, c := range test.command {
				command[i] = resp.StringValue(c)
			}

			if err = client.WriteArray(command); err != nil {
				t.Error(err)
			}
			res, _, err := client.ReadValue()
			if err != nil {
				t.Error(err)
			}

			if test.expectedError != nil {
				if !strings.Contains(res.Error().Error(), test.expectedError.Error()) {
					t.Errorf("expected error \"%s\", got \"%s\"", test.expectedError.Error(), err.Error())
				}
				return
			}

			if res.Integer() != test.expectedResponse {
				t.Errorf("expected response \"%d\", got \"%d\"", test.expectedResponse, res.Integer())
			}
		})
	}
}

func Test_HandleStrLen(t *testing.T) {
	conn, err := net.Dial("tcp", fmt.Sprintf("%s:%d", addr, port))
	if err != nil {
		t.Error(err)
	}
	client := resp.NewConn(conn)

	tests := []struct {
		name             string
		key              string
		presetValue      string
		command          []string
		expectedResponse int
		expectedError    error
	}{
		{
			name:             "Return the correct string length for an existing string",
			key:              "StrLenKey1",
			presetValue:      "Test String",
			command:          []string{"STRLEN", "StrLenKey1"},
			expectedResponse: len("Test String"),
			expectedError:    nil,
		},
		{
			name:             "If the string does not exist, return 0",
			key:              "StrLenKey2",
			presetValue:      "",
			command:          []string{"STRLEN", "StrLenKey2"},
			expectedResponse: 0,
			expectedError:    nil,
		},
		{
			name:             "Too few args",
			key:              "StrLenKey3",
			presetValue:      "",
			command:          []string{"STRLEN"},
			expectedResponse: 0,
			expectedError:    errors.New(constants.WrongArgsResponse),
		},
		{
			name:             "Too many args",
			key:              "StrLenKey4",
			presetValue:      "",
			command:          []string{"STRLEN", "StrLenKey4", "StrLenKey5"},
			expectedResponse: 0,
			expectedError:    errors.New(constants.WrongArgsResponse),
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			if test.presetValue != "" {
				if err = client.WriteArray([]resp.Value{
					resp.StringValue("SET"),
					resp.StringValue(test.key),
					resp.StringValue(test.presetValue),
				}); err != nil {
					t.Error(err)
				}
				res, _, err := client.ReadValue()
				if err != nil {
					t.Error(err)
				}

				if !strings.EqualFold(res.String(), "ok") {
					t.Errorf("expected preset response to be OK, got %s", res.String())
				}
			}

			command := make([]resp.Value, len(test.command))
			for i, c := range test.command {
				command[i] = resp.StringValue(c)
			}

			if err = client.WriteArray(command); err != nil {
				t.Error(err)
			}
			res, _, err := client.ReadValue()
			if err != nil {
				t.Error(err)
			}

			if test.expectedError != nil {
				if !strings.Contains(res.Error().Error(), test.expectedError.Error()) {
					t.Errorf("expected error \"%s\", got \"%s\"", test.expectedError.Error(), err.Error())
				}
				return
			}

			if res.Integer() != test.expectedResponse {
				t.Errorf("expected response \"%d\", got \"%d\"", test.expectedResponse, res.Integer())
			}
		})
	}
}

func Test_HandleSubStr(t *testing.T) {
	conn, err := net.Dial("tcp", fmt.Sprintf("%s:%d", addr, port))
	if err != nil {
		t.Error(err)
	}
	client := resp.NewConn(conn)

	tests := []struct {
		name             string
		key              string
		presetValue      string
		command          []string
		expectedResponse string
		expectedError    error
	}{
		{
			name:             "Return substring within the range of the string",
			key:              "SubStrKey1",
			presetValue:      "Test String One",
			command:          []string{"SUBSTR", "SubStrKey1", "5", "10"},
			expectedResponse: "String",
			expectedError:    nil,
		},
		{
			name:             "Return substring at the end of the string with exact end index",
			key:              "SubStrKey2",
			presetValue:      "Test String Two",
			command:          []string{"SUBSTR", "SubStrKey2", "12", "14"},
			expectedResponse: "Two",
			expectedError:    nil,
		},
		{
			name:             "Return substring at the end of the string with end index greater than length",
			key:              "SubStrKey3",
			presetValue:      "Test String Three",
			command:          []string{"SUBSTR", "SubStrKey3", "12", "75"},
			expectedResponse: "Three",
			expectedError:    nil,
		},
		{
			name:             "Return the substring at the start of the string with 0 start index",
			key:              "SubStrKey4",
			presetValue:      "Test String Four",
			command:          []string{"SUBSTR", "SubStrKey4", "0", "3"},
			expectedResponse: "Test",
			expectedError:    nil,
		},
		{
			// Return the substring with negative start index.
			// Substring should begin abs(start) from the end of the string when start is negative.
			name:             "Return the substring with negative start index",
			key:              "SubStrKey5",
			presetValue:      "Test String Five",
			command:          []string{"SUBSTR", "SubStrKey5", "-11", "10"},
			expectedResponse: "String",
			expectedError:    nil,
		},
		{
			// Return reverse substring with end index smaller than start index.
			// When end index is smaller than start index, the 2 indices are reversed.
			name:             "Return reverse substring with end index smaller than start index",
			key:              "SubStrKey6",
			presetValue:      "Test String Six",
			command:          []string{"SUBSTR", "SubStrKey6", "4", "0"},
			expectedResponse: "tseT",
			expectedError:    nil,
		},
		{
			name:          "Command too short",
			command:       []string{"SUBSTR", "key", "10"},
			expectedError: errors.New(constants.WrongArgsResponse),
		},
		{
			name:          "Command too long",
			command:       []string{"SUBSTR", "key", "10", "15", "20"},
			expectedError: errors.New(constants.WrongArgsResponse),
		},
		{
			name:          "Start index is not an integer",
			command:       []string{"SUBSTR", "key", "start", "10"},
			expectedError: errors.New("start and end indices must be integers"),
		},
		{
			name:          "End index is not an integer",
			command:       []string{"SUBSTR", "key", "0", "end"},
			expectedError: errors.New("start and end indices must be integers"),
		},
		{
			name:          "Non-existent key",
			command:       []string{"SUBSTR", "non-existent-key", "0", "10"},
			expectedError: errors.New("key non-existent-key does not exist"),
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			if test.presetValue != "" {
				if err = client.WriteArray([]resp.Value{
					resp.StringValue("SET"),
					resp.StringValue(test.key),
					resp.StringValue(test.presetValue),
				}); err != nil {
					t.Error(err)
				}
				res, _, err := client.ReadValue()
				if err != nil {
					t.Error(err)
				}

				if !strings.EqualFold(res.String(), "ok") {
					t.Errorf("expected preset response to be OK, got %s", res.String())
				}
			}

			command := make([]resp.Value, len(test.command))
			for i, c := range test.command {
				command[i] = resp.StringValue(c)
			}

			if err = client.WriteArray(command); err != nil {
				t.Error(err)
			}
			res, _, err := client.ReadValue()
			if err != nil {
				t.Error(err)
			}

			if test.expectedError != nil {
				if !strings.Contains(res.Error().Error(), test.expectedError.Error()) {
					t.Errorf("expected error \"%s\", got \"%s\"", test.expectedError.Error(), err.Error())
				}
				return
			}

			if res.String() != test.expectedResponse {
				t.Errorf("expected response \"%s\", got \"%s\"", test.expectedResponse, res.String())
			}
		})
	}
}