parseschedule.go

package _example

import (
	"context"
	_ "embed"
	"fmt"
	"regexp"
	"strings"
	"testing"
	"time"

	"github.com/cappuccinotm/grid"
	"github.com/cappuccinotm/grid/gctrl"
	"github.com/stretchr/testify/require"
)

//go:embed schedule.csv
var scheduleFile []byte

type timeSpan struct {
	Start time.Time
	End   time.Time
}

func (t *timeSpan) UnmarshalGrid(ctx context.Context, anchor grid.Anchor) error {
	v, err := anchor.Get(ctx, grid.RelativePos{})
	if err != nil {
		return fmt.Errorf("get value: %w", err)
	}

	tokens := strings.Split(strings.TrimSpace(v), "-")
	if len(tokens) != 2 {
		return fmt.Errorf("invalid period: %s", v)
	}

	if t.Start, err = time.Parse("15:04", tokens[0]); err != nil {
		return fmt.Errorf("parse start time: %w", err)
	}

	if t.End, err = time.Parse("15:04", tokens[1]); err != nil {
		return fmt.Errorf("parse end time: %w", err)
	}

	return nil
}

func TestSchedule(t *testing.T) {
	sheet := grid.CSV(scheduleFile)

	// This test represents a parser for Innopolis University schedule for BS4
	// students in 2023 winter/spring semester.
	// Thanks to the university for giving an idea of this library, as this 
	// schedule is a perfect example of a shit-like data that is hard to parse.

	// Lesson represents a single lesson.
	// Here anchor is placed on the 'LessonName' cell, all positions in tags are relative
	// to the anchor.
	//
	// Lesson itself is represented in the following way in the table:
	//     09:30-11:00 | ... | LessonName |
	//                 | ... | Teachers   |
	//   	           | ... | Room       |
	type Lesson struct {
		Name     string   `grid:"row:0,col:0"`
		Teachers string   `grid:"row:1,col:0"`
		Room     string   `grid:"row:2,col:0"`
		Span     timeSpan `grid:"row:0,col:$1"` // time span is always on the first column
	}

	dec := gctrl.NewDecoder(
		// groups
		gctrl.RepeatCols{
			// decoding starts from 0,0, so relative position to origin is the same as absolute in here
			From:  grid.RelativePos{Row: 1, Col: 1},
			Until: gctrl.EOF,
			Key:   gctrl.Value{At: grid.RelativePos{Row: 0, Col: 0}},
			// weekdays
			Nested: gctrl.RepeatCols{
				From:  grid.RelativePos{Row: +1, Col: -1},
				Until: gctrl.EOF,
				Key:   gctrl.Value{At: grid.RelativePos{Row: 0, Col: 0}},
				// lessons
				Nested: gctrl.RepeatRows{
					From: grid.RelativePos{Row: +1, Col: +1},
					Until: gctrl.Value{
						At:      grid.RelativePos{Row: 0, Col: -1},
						Matches: regexp.MustCompile(`MONDAY|TUESDAY|WEDNESDAY|THURSDAY|FRIDAY|SATURDAY|SUNDAY`),
					},
					Into: (*Lesson)(nil),
				},
			},
		},
	)

	var schedule map[string]map[string][]Lesson
	err := dec.Decode(sheet, &schedule)
	require.NoError(t, err)
}