package cli_test

import (
	"slices"
	"strings"
	"testing"

	"git.eeqj.de/sneak/bsdaily/internal/cli"
)

func TestParseTargetDates(t *testing.T) {
	t.Parallel()

	const oneDay = "2026-05-14"

	// want lists the expected days as YYYY-MM-DD.
	tests := []struct {
		name string
		date string
		from string
		to   string
		want []string
	}{
		{name: "no flags"},
		{name: "single date", date: "2026-06-27", want: []string{"2026-06-27"}},
		{
			name: "range across a month end", from: "2026-06-29", to: "2026-07-02",
			want: []string{"2026-06-29", "2026-06-30", "2026-07-01", "2026-07-02"},
		},
		{name: "range of one day", from: oneDay, to: oneDay, want: []string{oneDay}},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()

			got, err := cli.ParseTargetDates(tt.date, tt.from, tt.to)
			if err != nil {
				t.Fatalf("unexpected error: %v", err)
			}

			days := make([]string, 0, len(got))
			for _, day := range got {
				days = append(days, day.Format("2006-01-02"))
			}

			if !slices.Equal(days, tt.want) {
				t.Errorf("days = %v, want %v", days, tt.want)
			}
		})
	}
}

func TestParseTargetDatesErrors(t *testing.T) {
	t.Parallel()

	// wantErr is how the error message starts: for a malformed date, the
	// date parser's own explanation follows it.
	tests := []struct {
		name    string
		date    string
		from    string
		to      string
		wantErr string
	}{
		{
			name: "from after to", from: "2026-03-02", to: "2026-03-01",
			wantErr: "--from 2026-03-02 is after --to 2026-03-01",
		},
		{name: "from without to", from: "2026-04-01", wantErr: "--from requires --to"},
		{name: "to without from", to: "2026-04-02", wantErr: "--to requires --from"},
		{
			name: "date with from", date: "2026-01-05", from: "2026-01-06",
			wantErr: "--date and --from/--to are mutually exclusive",
		},
		{
			name: "date with from and to", date: "2026-01-07",
			from: "2026-01-08", to: "2026-01-09",
			wantErr: "--date and --from/--to are mutually exclusive",
		},
		{
			name: "malformed date", date: "27.06.2026",
			wantErr: `invalid --date "27.06.2026" (expected YYYY-MM-DD): `,
		},
		{
			name: "date that does not exist", date: "2026-02-30",
			wantErr: `invalid --date "2026-02-30" (expected YYYY-MM-DD): `,
		},
		{
			name: "malformed from", from: "2026-1-10", to: "2026-01-11",
			wantErr: `invalid --from "2026-1-10" (expected YYYY-MM-DD): `,
		},
		{
			name: "malformed to", from: "2026-01-12", to: "tomorrow",
			wantErr: `invalid --to "tomorrow" (expected YYYY-MM-DD): `,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()

			_, err := cli.ParseTargetDates(tt.date, tt.from, tt.to)
			if err == nil || !strings.HasPrefix(err.Error(), tt.wantErr) {
				t.Errorf("error = %v, want one starting %q", err, tt.wantErr)
			}
		})
	}
}