package membership

import (
	"fmt"
	"fuj-management/go/internal/domain/reconcile"
	"io"
	"strings"
	"time"
)

// printFeesTable writes a fixed-width adult-fees table to w.
// Mirrors scripts/calculate_fees.py main().
//
// Verify with:
//
//	PYTHONPATH=scripts:. python scripts/calculate_fees.py
func printFeesTable(w io.Writer, members []reconcile.Member, sortedMonths []string) {
	type row struct {
		name string
		fees map[string]reconcile.FeeData
	}

	var adults []row
	for _, m := range members {
		if m.Tier == "A" {
			adults = append(adults, row{name: m.Name, fees: m.Fees})
		}
	}

	if len(adults) == 0 {
		fmt.Fprintln(w, "No data.")
		return
	}

	monthLabel := func(m string) string {
		t, err := time.Parse("2006-01", m)
		if err != nil {
			return m
		}
		return t.Format("Jan 2006")
	}

	const colWidth = 15

	nameWidth := 20
	for _, r := range adults {
		if len(r.name) > nameWidth {
			nameWidth = len(r.name)
		}
	}

	// separator length: nameWidth + N*(colWidth+3) where +3 is " | "
	sepLen := nameWidth + len(sortedMonths)*(colWidth+3)

	// Header row
	fmt.Fprintf(w, "%-*s", nameWidth, "Member")
	for _, m := range sortedMonths {
		fmt.Fprintf(w, " | %*s", colWidth, monthLabel(m))
	}
	fmt.Fprintln(w)
	fmt.Fprintln(w, strings.Repeat("-", sepLen))

	// Member rows + accumulate monthly totals
	monthlyTotals := make(map[string]int, len(sortedMonths))
	for _, r := range adults {
		fmt.Fprintf(w, "%-*s", nameWidth, r.name)
		for _, m := range sortedMonths {
			fd := r.fees[m]
			monthlyTotals[m] += fd.Expected
			var cell string
			if fd.Attendance > 0 {
				cell = fmt.Sprintf("%d CZK (%d)", fd.Expected, fd.Attendance)
			} else {
				cell = "-"
			}
			fmt.Fprintf(w, " | %*s", colWidth, cell)
		}
		fmt.Fprintln(w)
	}

	// Totals row
	fmt.Fprintln(w, strings.Repeat("-", sepLen))
	fmt.Fprintf(w, "%-*s", nameWidth, "TOTAL")
	for _, m := range sortedMonths {
		cell := fmt.Sprintf("%d CZK", monthlyTotals[m])
		fmt.Fprintf(w, " | %*s", colWidth, cell)
	}
	fmt.Fprintln(w)
}