package pagination

import (
	"testing"
)

func TestDefaultPagination(t *testing.T) {
	p := DefaultPagination()
	if p.Page != 1 {
		t.Errorf("expected default page 1, got %d", p.Page)
	}
	if p.PageSize != 20 {
		t.Errorf("expected default page_size 20, got %d", p.PageSize)
	}
}

func TestPaginationParams_Offset(t *testing.T) {
	tests := []struct {
		name       string
		page       int
		pageSize   int
		wantOffset int
	}{
		{"page 1", 1, 20, 0},
		{"page 2", 2, 20, 20},
		{"page 5", 5, 20, 80},
		{"zero page", 0, 20, 0},
		{"negative page", -1, 20, 0},
		{"page 1 size 10", 1, 10, 0},
		{"page 3 size 10", 3, 10, 20},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			p := PaginationParams{Page: tc.page, PageSize: tc.pageSize}
			if got := p.Offset(); got != tc.wantOffset {
				t.Errorf("expected offset %d, got %d", tc.wantOffset, got)
			}
		})
	}
}

func TestPaginationParams_Limit(t *testing.T) {
	tests := []struct {
		name     string
		pageSize int
		want     int
	}{
		{"default", 20, 20},
		{"size 10", 10, 10},
		{"size 50", 50, 50},
		{"size 100", 100, 100},
		{"max cap", 101, 100},
		{"zero size", 0, 20},
		{"negative size", -1, 20},
		{"size 1", 1, 1},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			p := PaginationParams{PageSize: tc.pageSize}
			if got := p.Limit(); got != tc.want {
				t.Errorf("expected limit %d, got %d", tc.want, got)
			}
		})
	}
}

func TestPaginationParams_OffsetAndLimit(t *testing.T) {
	p := PaginationParams{Page: 3, PageSize: 15}
	if got := p.Offset(); got != 30 {
		t.Errorf("expected offset 30, got %d", got)
	}
	if got := p.Limit(); got != 15 {
		t.Errorf("expected limit 15, got %d", got)
	}
}