package server

import (
	"fmt"
	"strconv"
	"strings"
)

var imageAspectRatioSeparators = strings.NewReplacer(
	"：", ":",
	"／", ":",
	"/", ":",
	"×", ":",
	"*", ":",
	"x", ":",
	"X", ":",
)

var canonicalImageAspectRatioLabels = map[string]string{
	"7:3":  "21:9",
	"16:9": "16:9",
	"4:3":  "4:3",
	"3:2":  "3:2",
	"1:1":  "1:1",
	"9:16": "9:16",
	"3:4":  "3:4",
	"2:3":  "2:3",
	"5:4":  "5:4",
	"4:5":  "4:5",
}

var seedreamAspectRatioSizes = map[string]string{
	"21:9": "2520x1080",
	"16:9": "2048x1152",
	"4:3":  "2048x1536",
	"3:2":  "2304x1536",
	"1:1":  "2048x2048",
	"9:16": "1152x2048",
	"3:4":  "1536x2048",
	"2:3":  "1536x2304",
	"5:4":  "1920x1536",
	"4:5":  "1536x1920",
}

var exactImageSizeAspectRatios = map[string]string{
	"1024x1024": "1:1",
	"1920x1920": "1:1",
	"1536x1024": "3:2",
	"1024x1536": "2:3",
	"1792x1024": "16:9",
	"1024x1792": "9:16",
}

func normalizeImageAspectRatio(value string) string {
	width, height, ok := parseAspectRatioDimensions(value)
	if !ok {
		return strings.TrimSpace(value)
	}
	return canonicalAspectRatioLabel(width, height)
}

func parseAspectRatioDimensions(value string) (int, int, bool) {
	value = strings.TrimSpace(value)
	if value == "" {
		return 0, 0, false
	}

	normalized := imageAspectRatioSeparators.Replace(value)
	parts := strings.Split(normalized, ":")
	if len(parts) != 2 {
		return 0, 0, false
	}

	width, errWidth := strconv.Atoi(strings.TrimSpace(parts[0]))
	height, errHeight := strconv.Atoi(strings.TrimSpace(parts[1]))
	if errWidth != nil || errHeight != nil || width <= 0 || height <= 0 {
		return 0, 0, false
	}
	return width, height, true
}

func canonicalAspectRatioLabel(width, height int) string {
	rw, rh := reduceImageRatio(width, height)
	key := fmt.Sprintf("%d:%d", rw, rh)
	if label, ok := canonicalImageAspectRatioLabels[key]; ok {
		return label
	}
	return key
}

func reduceImageRatio(width, height int) (int, int) {
	g := imageGCD(width, height)
	if g == 0 {
		return width, height
	}
	return width / g, height / g
}

func imageGCD(a, b int) int {
	for b != 0 {
		a, b = b, a%b
	}
	if a < 0 {
		return -a
	}
	return a
}

func parseExactImageSize(value string) (int, int, bool) {
	value = strings.TrimSpace(strings.ToLower(value))
	if value == "" {
		return 0, 0, false
	}
	parts := strings.Split(value, "x")
	if len(parts) != 2 {
		return 0, 0, false
	}
	width, errWidth := strconv.Atoi(strings.TrimSpace(parts[0]))
	height, errHeight := strconv.Atoi(strings.TrimSpace(parts[1]))
	if errWidth != nil || errHeight != nil || width <= 0 || height <= 0 {
		return 0, 0, false
	}
	return width, height, true
}

func normalizeImageSizeToken(value string) string {
	value = strings.TrimSpace(value)
	if value == "" {
		return ""
	}
	switch strings.ToUpper(value) {
	case "1K", "2K", "4K":
		return strings.ToUpper(value)
	}
	width, height, ok := parseExactImageSize(value)
	if !ok {
		return value
	}
	return fmt.Sprintf("%dx%d", width, height)
}

func deriveAspectRatioFromImageSize(value string) string {
	value = normalizeImageSizeToken(value)
	if ratio, ok := exactImageSizeAspectRatios[value]; ok {
		return ratio
	}
	width, height, ok := parseExactImageSize(value)
	if !ok {
		if ratio := normalizeImageAspectRatio(value); ratio != "" {
			return ratio
		}
		return ""
	}
	return canonicalAspectRatioLabel(width, height)
}

func geminiImageSizeFromValue(value string) string {
	value = normalizeImageSizeToken(value)
	switch value {
	case "1K", "2K", "4K":
		return value
	}
	width, height, ok := parseExactImageSize(value)
	if !ok {
		return ""
	}
	longEdge := width
	if height > longEdge {
		longEdge = height
	}
	switch {
	case longEdge <= 1024:
		return "1K"
	case longEdge <= 2560:
		return "2K"
	default:
		return "4K"
	}
}

func seedreamImageSizeFromAspectRatio(value string) string {
	if ratio := normalizeImageAspectRatio(value); ratio != "" {
		if size, ok := seedreamAspectRatioSizes[ratio]; ok {
			return size
		}
	}
	return ""
}

func supportedSeedreamSize(modelID, value string) bool {
	value = strings.ToUpper(strings.TrimSpace(value))
	if value == "" {
		return false
	}
	_, ok := supportedSeedreamSizes(modelID)[value]
	return ok
}