package membership

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

// printReconcileReport writes the full balance report to w.
// Mirrors scripts/match_payments.py print_report().
//
// Verify with:
//
//	PYTHONPATH=scripts:. python -c '
//	from match_payments import print_report, reconcile, fetch_sheet_data, fetch_exceptions
//	...'
func printReconcileReport(w io.Writer, result reconcile.Result, sortedMonths []string) {
	monthLabel := func(m string) string {
		t, err := time.Parse("2006-01", m)
		if err != nil {
			return m
		}
		return t.Format("Jan 2006")
	}

	const colWidth = 10

	// Collect adults only
	type memberEntry struct {
		name string
		data reconcile.MemberResult
	}
	var adults []memberEntry
	for name, data := range result.Members {
		if data.Tier == "A" {
			adults = append(adults, memberEntry{name: name, data: data})
		}
	}
	sort.Slice(adults, func(i, j int) bool { return adults[i].name < adults[j].name })

	// Header banner
	fmt.Fprintln(w, strings.Repeat("=", 80))
	fmt.Fprintln(w, "PAYMENT RECONCILIATION REPORT")
	fmt.Fprintln(w, strings.Repeat("=", 80))

	// Name column width
	nameWidth := 20
	for _, e := range adults {
		if len(e.name) > nameWidth {
			nameWidth = len(e.name)
		}
	}

	// sep length: nameWidth + (nMonths+1)*(colWidth+3)
	sepLen := nameWidth + (len(sortedMonths)+1)*(colWidth+3)

	// Summary table header — Python does print(..., end="") then print(f" | {'Balance':>10}")
	fmt.Fprintf(w, "\n%-*s", nameWidth, "Member")
	for _, m := range sortedMonths {
		fmt.Fprintf(w, " | %*s", colWidth, monthLabel(m))
	}
	fmt.Fprintf(w, " | %*s\n", colWidth, "Balance")
	fmt.Fprintln(w, strings.Repeat("-", sepLen))

	var totalExpected, totalPaid int

	for _, e := range adults {
		fmt.Fprintf(w, "%-*s", nameWidth, e.name)
		memberBalance := 0
		for _, m := range sortedMonths {
			md := e.data.Months[m]
			expected := md.Expected
			paid := int(md.Paid)
			totalExpected += expected
			totalPaid += paid

			var cell string
			switch {
			case expected == 0 && paid == 0:
				cell = "-"
			case paid >= expected && expected > 0:
				cell = "OK"
			case paid > 0:
				cell = fmt.Sprintf("%d/%d", paid, expected)
			default:
				cell = fmt.Sprintf("UNPAID %d", expected)
			}

			memberBalance += paid - expected
			fmt.Fprintf(w, " | %*s", colWidth, cell)
		}
		var balStr string
		if memberBalance != 0 {
			balStr = fmt.Sprintf("%+d", memberBalance)
		} else {
			balStr = "0"
		}
		fmt.Fprintf(w, " | %*s\n", colWidth, balStr)
	}

	// TOTAL footer
	fmt.Fprintln(w, strings.Repeat("-", sepLen))
	fmt.Fprintf(w, "%-*s", nameWidth, "TOTAL")
	for range sortedMonths {
		fmt.Fprintf(w, " | %*s", colWidth, "")
	}
	balance := totalPaid - totalExpected
	fmt.Fprintf(w, " | Expected: %d, Paid: %d, Balance: %+d\n", totalExpected, totalPaid, balance)

	// Credits
	var credits []memberEntry
	for _, e := range adults {
		if e.data.TotalBalance > 0 {
			credits = append(credits, e)
		}
	}
	// also non-adult members with positive balance
	for name, data := range result.Members {
		if data.Tier != "A" && data.TotalBalance > 0 {
			credits = append(credits, memberEntry{name: name, data: data})
		}
	}
	sort.Slice(credits, func(i, j int) bool { return credits[i].name < credits[j].name })
	if len(credits) > 0 {
		fmt.Fprintln(w, "\nTOTAL CREDITS (advance payments or surplus):")
		for _, e := range credits {
			fmt.Fprintf(w, "  %s: %d CZK\n", e.name, e.data.TotalBalance)
		}
	}

	// Debts
	var debts []memberEntry
	for _, e := range adults {
		if e.data.TotalBalance < 0 {
			debts = append(debts, e)
		}
	}
	for name, data := range result.Members {
		if data.Tier != "A" && data.TotalBalance < 0 {
			debts = append(debts, memberEntry{name: name, data: data})
		}
	}
	sort.Slice(debts, func(i, j int) bool { return debts[i].name < debts[j].name })
	if len(debts) > 0 {
		fmt.Fprintln(w, "\nTOTAL DEBTS (missing payments):")
		for _, e := range debts {
			fmt.Fprintf(w, "  %s: %d CZK\n", e.name, -e.data.TotalBalance)
		}
	}

	// Unmatched transactions
	if len(result.Unmatched) > 0 {
		fmt.Fprintln(w, "\nUNMATCHED TRANSACTIONS (need manual review)")
		fmt.Fprintf(w, "  %-12s %10s  %-30s %s\n", "Date", "Amount", "Sender", "Message")
		fmt.Fprintf(w, "  %-12s %10s  %-30s %-30s\n",
			strings.Repeat("-", 12), strings.Repeat("-", 10),
			strings.Repeat("-", 30), strings.Repeat("-", 30))
		for _, tx := range result.Unmatched {
			fmt.Fprintf(w, "  %-12s %10.0f  %-30s %s\n",
				tx.Date, tx.Amount, tx.Sender, tx.Message)
		}
	}

	// Matched transaction details
	fmt.Fprintln(w, "\nMATCHED TRANSACTION DETAILS")
	for _, e := range adults {
		hasPayments := false
		for _, m := range sortedMonths {
			if len(e.data.Months[m].Transactions) > 0 {
				hasPayments = true
				break
			}
		}
		if !hasPayments {
			continue
		}
		fmt.Fprintf(w, "\n  %s:\n", e.name)
		for _, m := range sortedMonths {
			for _, tx := range e.data.Months[m].Transactions {
				conf := ""
				if tx.Confidence == "review" {
					conf = " [REVIEW]"
				}
				fmt.Fprintf(w, "    %s: %.0f CZK from %s — \"%s\"%s\n",
					monthLabel(m), tx.Amount, tx.Sender, tx.Message, conf)
			}
		}
	}
}