// Package tournament shows football competition results.
package tournament
import (
	"encoding/csv"
	"fmt"
	"io"
	"sort"
	"strings"
)
// teamData stores the team's name, wins, draws and losses.
type teamData struct {
	name string
	w    int
	d    int
	l    int
}
type table []teamData
// Tally writes results table created from input to w.
func Tally(input io.Reader, w io.Writer) error {
	r := csv.NewReader(input)
	r.Comma = ';'
	r.Comment = '#'
	records, err := r.ReadAll()
	if err != nil {
		return err
	}
	results := table{}
	for _, row := range records {
		if len(row) != 3 {
			return fmt.Errorf("row length should be 3, got: %d %q", len(row), row)
		}
		if results.getID(row[0]) == -1 {
			results = append(results, teamData{row[0], 0, 0, 0})
		}
		if results.getID(row[1]) == -1 {
			results = append(results, teamData{row[1], 0, 0, 0})
		}
		switch row[2] {
		case "win":
			results[results.getID(row[0])].w++
			results[results.getID(row[1])].l++
		case "loss":
			results[results.getID(row[1])].w++
			results[results.getID(row[0])].l++
		case "draw":
			results[results.getID(row[1])].d++
			results[results.getID(row[0])].d++
		default:
			return fmt.Errorf("unexpected result: %q", row[2])
		}
	}
	sort.Slice(results, func(i, j int) bool {
		if 3*results[i].w+results[i].d > 3*results[j].w+results[j].d {
			return true
		} else if 3*results[i].w+results[i].d == 3*results[j].w+results[j].d {
			if strings.Compare(results[i].name, results[j].name) == -1 {
				return true
			}
		}
		return false
	})
	buf := strings.Builder{}
	if _, err := buf.WriteString(
		fmt.Sprintf("%-30s %s\n", "Team", "| MP |  W |  D |  L |  P")); err != nil {
		return err
	}
	for _, t := range results {
		if _, err := buf.WriteString(
			fmt.Sprintf("%-30s | %2d | %2d | %2d | %2d | %2d\n",
				t.name, t.w+t.d+t.l, t.w, t.d, t.l, 3*t.w+t.d)); err != nil {
			return err
		}
	}
	if _, err = w.Write([]byte(buf.String())); err != nil {
		return err
	}
	return nil
}
func (t table) getID(name string) int {
	for i, item := range t {
		if item.name == name {
			return i
		}
	}
	return -1
}