// Copyright (c) 2026 Storm Dragon
// Authors: Storm Dragon, Angus Kola
// SPDX-License-Identifier: GPL-3.0-or-later

package presentation

import (
	"fmt"
	"slices"
	"strings"

	"git.stormux.org/storm/cthulhu/internal/atspi"
)

func calcColumnLabel(column int) string {
	label := ""
	for column++; column > 0; column = (column - 1) / 26 {
		label = string(rune('A'+(column-1)%26)) + label
	}
	return label
}

func calcCellLabel(cell atspi.LibreOfficeCell) string {
	return fmt.Sprintf("%s%d", calcColumnLabel(cell.Column), cell.Row+1)
}

// LibreOfficeSelectionText formats copied metadata only. A large selection's
// endpoints never imply a filled rectangle. Small disjoint selections retain
// their gaps; at most eight rectangles are spoken before using a count.
func LibreOfficeSelectionText(selection atspi.LibreOfficeSelection, action string) string {
	if selection.Kind == "all" {
		return "All cells " + action + "."
	}
	if selection.Count == 0 {
		return ""
	}
	if !selection.Complete || len(selection.Cells) > 64 {
		return libreOfficeSelectionCount(selection, action)
	}
	cells := slices.Clone(selection.Cells)
	slices.SortFunc(cells, func(a, b atspi.LibreOfficeCell) int {
		if a.Row != b.Row {
			return a.Row - b.Row
		}
		return a.Column - b.Column
	})
	cells = slices.Compact(cells)
	type rectangle struct{ first, last atspi.LibreOfficeCell }
	var ranges []rectangle
	for index := 0; index < len(cells); {
		first, last := cells[index], cells[index]
		index++
		for index < len(cells) && (selection.Kind == "rows" && cells[index].Row == last.Row+1 ||
			selection.Kind != "rows" && cells[index].Row == last.Row && cells[index].Column == last.Column+1) {
			last = cells[index]
			index++
		}
		merged := false
		if selection.Kind == "cells" {
			for i := range ranges {
				previous := &ranges[i]
				if previous.first.Column == first.Column && previous.last.Column == last.Column && previous.last.Row+1 == first.Row {
					previous.last.Row = last.Row
					merged = true
					break
				}
			}
		}
		if !merged {
			ranges = append(ranges, rectangle{first, last})
		}
	}
	if len(ranges) > 8 {
		return libreOfficeSelectionCount(selection, action)
	}
	var messages []string
	for _, span := range ranges {
		first, last := calcCellLabel(span.first), calcCellLabel(span.last)
		singular, plural := "Cell", "Cells"
		if selection.Kind == "rows" {
			first, last = fmt.Sprint(span.first.Row+1), fmt.Sprint(span.last.Row+1)
			singular, plural = "Row", "Rows"
		} else if selection.Kind == "columns" {
			first, last = calcColumnLabel(span.first.Column), calcColumnLabel(span.last.Column)
			singular, plural = "Column", "Columns"
		}
		if first == last {
			messages = append(messages, fmt.Sprintf("%s %s %s.", singular, first, action))
		} else {
			messages = append(messages, fmt.Sprintf("%s %s to %s %s.", plural, first, last, action))
		}
	}
	return strings.Join(messages, " ")
}

func libreOfficeSelectionCount(selection atspi.LibreOfficeSelection, action string) string {
	prefix := ""
	if selection.CountLimited {
		prefix = "At least "
	}
	return fmt.Sprintf("%s%d %s %s.", prefix, selection.Count, selection.Kind, action)
}