package pagination

import (
	"testing"

	"github.com/stretchr/testify/assert"
)

func TestGetPage(t *testing.T) {
	type args[T any] struct {
		items  []T
		first  *int
		after  *string
		last   *int
		before *string
		max    int
		fn     func(T) string
	}
	type testCase[T any] struct {
		name         string
		args         args[T]
		wantItems    []T
		wantPageInfo PageInfo
	}
	tests := []testCase[string]{
		{
			name:         "nil items",
			args:         args[string]{max: 10},
			wantItems:    nil,
			wantPageInfo: PageInfo{},
		},
		{
			name:         "empty items",
			args:         args[string]{items: []string{}, max: 10},
			wantItems:    nil,
			wantPageInfo: PageInfo{},
		},
		{
			name:      "first 2",
			args:      args[string]{items: []string{"1", "2", "3"}, first: ptr(2), max: 10, fn: func(s string) string { return s }},
			wantItems: []string{"1", "2"},
			wantPageInfo: PageInfo{
				StartCursor: ptr("MQ=="),
				HasNextPage: true,
				EndCursor:   ptr("Mg=="),
			},
		},
		{
			name:      "first 10",
			args:      args[string]{items: []string{"1", "2", "3"}, first: ptr(10), max: 10, fn: func(s string) string { return s }},
			wantItems: []string{"1", "2", "3"},
			wantPageInfo: PageInfo{
				StartCursor: ptr("MQ=="),
				HasNextPage: false,
				EndCursor:   ptr("Mw=="),
			},
		},
		{
			name:      "after 2",
			args:      args[string]{items: []string{"1", "2", "3", "4"}, first: ptr(2), after: ptr("Mg=="), max: 10, fn: func(s string) string { return s }},
			wantItems: []string{"3", "4"},
			wantPageInfo: PageInfo{
				StartCursor:     ptr("Mw=="),
				HasNextPage:     false,
				HasPreviousPage: true,
				EndCursor:       ptr("NA=="),
			},
		},
		{
			name:      "end of items",
			args:      args[string]{items: []string{"1", "2", "3"}, first: ptr(2), after: ptr("Mg=="), max: 10, fn: func(s string) string { return s }},
			wantItems: []string{"3"},
			wantPageInfo: PageInfo{
				StartCursor:     ptr("Mw=="),
				HasNextPage:     false,
				HasPreviousPage: true,
				EndCursor:       ptr("Mw=="),
			},
		},
		{
			name:      "last 2",
			args:      args[string]{items: []string{"1", "2", "3"}, last: ptr(2), max: 10, fn: func(s string) string { return s }},
			wantItems: []string{"2", "3"},
			wantPageInfo: PageInfo{
				StartCursor:     ptr("Mg=="),
				HasNextPage:     false,
				HasPreviousPage: true,
				EndCursor:       ptr("Mw=="),
			},
		},
		{
			name:      "before 3",
			args:      args[string]{items: []string{"1", "2", "3"}, last: ptr(2), before: ptr("Mw=="), max: 10, fn: func(s string) string { return s }},
			wantItems: []string{"1", "2"},
			wantPageInfo: PageInfo{
				StartCursor:     ptr("MQ=="),
				HasNextPage:     true,
				HasPreviousPage: false,
				EndCursor:       ptr("Mg=="),
			},
		},
		{
			name:      "before 2",
			args:      args[string]{items: []string{"1", "2", "3"}, last: ptr(2), before: ptr("Mg=="), max: 10, fn: func(s string) string { return s }},
			wantItems: []string{"1"},
			wantPageInfo: PageInfo{
				StartCursor:     ptr("MQ=="),
				HasNextPage:     true,
				HasPreviousPage: false,
				EndCursor:       ptr("MQ=="),
			},
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, got1 := GetPage(tt.args.items, tt.args.first, tt.args.after, tt.args.last, tt.args.before, tt.args.max, tt.args.fn)
			assert.Equalf(t, tt.wantItems, got, "GetPage(%v, %v, %v, %v, %v, %v)", tt.args.items, tt.args.first, tt.args.after, tt.args.last, tt.args.before, tt.args.max)
			assert.Equalf(t, tt.wantPageInfo, got1, "GetPage(%v, %v, %v, %v, %v, %v)", tt.args.items, tt.args.first, tt.args.after, tt.args.last, tt.args.before, tt.args.max)
		})
	}
}