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

package app

import (
	"context"
	"errors"
	"fmt"
	"strconv"
	"strings"
	"time"

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

type characterAttributeSource interface {
	ReadCharacterAttributes(context.Context, atspi.ObjectID) (atspi.CharacterAttributes, error)
}

type characterAttributeResult struct {
	object   atspi.ObjectID
	sequence uint64
	values   map[string]string
	err      error
}

type characterAttributeRequest struct {
	object   atspi.ObjectID
	sequence uint64
}

type characterAttributeReader struct {
	requests chan characterAttributeRequest
	results  chan characterAttributeResult
	cancel   context.CancelFunc
	done     chan struct{}
}

// This reader owns one native query at a time and one waiting request. Native
// work stays on AT-SPI's GLib owner; the event loop remains responsive.
func startCharacterAttributeReader(parent context.Context, adapter Adapter) *characterAttributeReader {
	ctx, cancel := context.WithCancel(parent)
	reader := &characterAttributeReader{
		requests: make(chan characterAttributeRequest, 1),
		results:  make(chan characterAttributeResult, 1),
		cancel:   cancel,
		done:     make(chan struct{}),
	}
	source, supported := adapter.(characterAttributeSource)
	go func() {
		defer close(reader.done)
		for {
			select {
			case <-ctx.Done():
				return
			case request := <-reader.requests:
				result := characterAttributeResult{object: request.object, sequence: request.sequence}
				if supported && request.object.Valid() {
					deadline, cancel := context.WithTimeout(ctx, 1200*time.Millisecond)
					attributes, err := source.ReadCharacterAttributes(deadline, request.object)
					cancel()
					result.values, result.err = attributes.Values, err
				} else {
					result.err = atspi.ErrStaleObject
				}
				select {
				case reader.results <- result:
				case <-ctx.Done():
					return
				}
			}
		}
	}()
	return reader
}

func (reader *characterAttributeReader) request(object atspi.ObjectID, sequence uint64) {
	if !object.Valid() {
		return
	}
	request := characterAttributeRequest{object: object, sequence: sequence}
	select {
	case reader.requests <- request:
	default:
		select {
		case <-reader.requests:
		default:
		}
		select {
		case reader.requests <- request:
		default:
		}
	}
}

func (reader *characterAttributeReader) stop() {
	reader.cancel()
	<-reader.done
}

func presentCharacterAttributes(speech speechEnqueuer, result characterAttributeResult, useColorNames bool, configured ...config.TextAttributeSettings) {
	if errors.Is(result.err, atspi.ErrStaleObject) || errors.Is(result.err, context.Canceled) {
		return
	}
	message := "Text attributes are unavailable."
	if result.err == nil {
		if parts := spokenCharacterAttributes(result.values, useColorNames, configured...); len(parts) != 0 {
			message = strings.Join(parts, ", ")
		} else {
			message = "No text attributes to speak."
		}
	}
	speech.Interrupt()
	speech.Enqueue(speechRequest{Text: message, Role: "system", Cause: "character-attributes"})
}

var characterAttributeOrder = [...]struct {
	key, label, ignore string
}{
	{"size", "font size", ""},
	{"family-name", "font family", ""},
	{"weight", "weight", "400"},
	{"indent", "indent", "0"},
	{"underline", "underline", "none"},
	{"strikethrough", "strikethrough", "false"},
	{"justification", "justification", "left"},
	{"style", "style", "normal"},
	{"paragraph-style", "paragraph style", ""},
	{"text-spelling", "spelling", "none"},
	{"fg-color", "foreground color", ""},
	{"bg-color", "background color", ""},
}

func spokenCharacterAttributes(values map[string]string, useColorNames bool, configured ...config.TextAttributeSettings) []string {
	parts := make([]string, 0, len(characterAttributeOrder))
	order := make([]struct{ key, label, ignore string }, 0, len(characterAttributeOrder))
	if len(configured) == 0 {
		order = append(order, characterAttributeOrder[:]...)
	} else {
		for _, choice := range configured[0].Choices {
			if !choice.Speak {
				continue
			}
			for _, known := range characterAttributeOrder {
				if choice.Key == known.key {
					order = append(order, known)
					break
				}
			}
		}
	}
	for _, attribute := range order {
		if attribute.key == "text-spelling" {
			if atspi.TextAttributesMisspelled(values) {
				parts = append(parts, "misspelled")
			}
			continue
		}
		value := strings.TrimSpace(values[attribute.key])
		if value == "" || value == attribute.ignore || value == "0" && attribute.ignore == "0" {
			continue
		}
		switch attribute.key {
		case "weight":
			if number, ok := parseAttributeInteger(value); value == "bold" || ok && number > 400 {
				parts = append(parts, "bold")
				continue
			}
		case "family-name":
			value = strings.Trim(strings.TrimSpace(strings.Split(value, ",")[0]), "\"")
		case "fg-color", "bg-color":
			if color, ok := describeAttributeColor(value, useColorNames); ok {
				value = color
			}
		}
		parts = append(parts, attribute.label+": "+value)
	}
	return parts
}

func parseAttributeInteger(value string) (int, bool) {
	number, err := strconv.Atoi(value)
	return number, err == nil
}

func describeAttributeColor(value string, useColorNames bool) (string, bool) {
	red, green, blue, ok := parseAttributeColor(value)
	if !ok {
		return "", false
	}
	if useColorNames {
		return nearestCSSColor(red, green, blue), true
	}
	return fmt.Sprintf("%d %d %d", red, green, blue), true
}

func parseAttributeColor(value string) (int, int, int, bool) {
	value = strings.ToLower(strings.TrimSpace(value))
	if strings.HasPrefix(value, "#") {
		if len(value) == 4 {
			value = "#" + strings.Repeat(value[1:2], 2) + strings.Repeat(value[2:3], 2) + strings.Repeat(value[3:4], 2)
		}
		if len(value) != 7 {
			return 0, 0, 0, false
		}
		var channels [3]int
		for index := range channels {
			number, err := strconv.ParseUint(value[1+index*2:3+index*2], 16, 8)
			if err != nil {
				return 0, 0, 0, false
			}
			channels[index] = int(number)
		}
		return channels[0], channels[1], channels[2], true
	}
	value = strings.TrimPrefix(value, "rgb(")
	value = strings.TrimSuffix(value, ")")
	fields := strings.Split(value, ",")
	if len(fields) != 3 {
		return 0, 0, 0, false
	}
	var channels [3]int
	for index, field := range fields {
		number, err := strconv.Atoi(strings.TrimSpace(field))
		if err != nil || number < 0 || number > 65535 {
			return 0, 0, 0, false
		}
		channels[index] = number
	}
	if channels[0] > 255 || channels[1] > 255 || channels[2] > 255 {
		for index, number := range channels {
			channels[index] = (number*255 + 32767) / 65535
		}
	}
	return channels[0], channels[1], channels[2], true
}

func nearestCSSColor(red, green, blue int) string {
	hex := fmt.Sprintf("#%02x%02x%02x", red, green, blue)
	if name := cssColorNames[hex]; name != "" {
		return name
	}
	bestDistance, secondDistance := int(^uint(0)>>1), int(^uint(0)>>1)
	bestHex, secondHex := "", ""
	for candidate := range cssColorNames {
		r, g, b, _ := parseAttributeColor(candidate)
		distance := (r-red)*(r-red) + (g-green)*(g-green) + (b-blue)*(b-blue)
		if distance < bestDistance || distance == bestDistance && candidate < bestHex {
			secondDistance, secondHex = bestDistance, bestHex
			bestDistance, bestHex = distance, candidate
		} else if distance < secondDistance || distance == secondDistance && candidate < secondHex {
			secondDistance, secondHex = distance, candidate
		}
	}
	if (bestHex == "#000000" || bestHex == "#ffffff") && secondHex != "" && secondDistance-bestDistance < bestDistance {
		bestHex = secondHex
	}
	return cssColorNames[bestHex]
}