package application

import (
	"encoding/json"
	"fmt"
	"regexp"
	"strings"
	"unicode/utf8"

	"img_infinite_canvas/internal/domain/design"
)

const (
	shortMemoryMessageLimit = 6
	shortMemoryNodeLimit    = 8
	longMemoryArtifactLimit = 16
	longMemoryDecisionLimit = 10
	shortMemoryMaxRunes     = 2400
	longMemoryMaxRunes      = 3200
)

var agentMemoryURLPattern = regexp.MustCompile(`https?://\S+`)

func buildAgentMemory(project design.Project, prompt string, mode string, messages []design.AgentChatMessage) design.AgentMemory {
	return design.AgentMemory{
		ShortTerm: buildShortMemory(project, prompt, mode, messages),
		LongTerm:  buildLongMemory(project),
	}
}

func buildShortMemory(project design.Project, prompt string, mode string, messages []design.AgentChatMessage) string {
	memoryMessages := visibleAgentMemoryMessages(project.Messages)
	sections := []string{
		"Current turn:",
		"- mode: " + strings.TrimSpace(mode),
		"- user request: " + strings.TrimSpace(prompt),
	}
	if inline := inlineInputMemory(messages); inline != "" {
		sections = append(sections, "Inline input:", inline)
	}
	if recent := recentMessageMemory(memoryMessages, shortMemoryMessageLimit); recent != "" {
		sections = append(sections, "Recent conversation:", recent)
	}
	if canvas := canvasNodeMemory(project.Nodes, shortMemoryNodeLimit); canvas != "" {
		sections = append(sections, "Visible canvas:", canvas)
	}
	return clampMemoryBlock(strings.Join(sections, "\n"), shortMemoryMaxRunes)
}

func buildLongMemory(project design.Project) string {
	memoryMessages := visibleAgentMemoryMessages(project.Messages)
	sections := []string{}
	if strings.TrimSpace(project.Title) != "" || strings.TrimSpace(project.Brief) != "" {
		sections = append(sections, "Project identity:")
		if strings.TrimSpace(project.Title) != "" {
			sections = append(sections, "- title: "+strings.TrimSpace(project.Title))
		}
		if strings.TrimSpace(project.Brief) != "" {
			sections = append(sections, "- brief: "+shortenMemoryText(project.Brief, 360))
		}
	}
	if decisions := durableDecisionMemory(memoryMessages, longMemoryDecisionLimit); decisions != "" {
		sections = append(sections, "Durable user decisions and preferences:", decisions)
	}
	if artifacts := completedArtifactMemory(project.Nodes, longMemoryArtifactLimit); artifacts != "" {
		sections = append(sections, "Completed canvas artifacts:", artifacts)
	}
	if research := researchMemory(memoryMessages); research != "" {
		sections = append(sections, "Prior web research:", research)
	}
	if len(sections) == 0 {
		return "none"
	}
	return clampMemoryBlock(strings.Join(sections, "\n"), longMemoryMaxRunes)
}

func visibleAgentMemoryMessages(messages []design.Message) []design.Message {
	hiddenThreads := make(map[string]bool)
	for _, message := range messages {
		if message.ThreadID == "" {
			continue
		}
		if isCanvasActionMemoryMessage(message) || message.Name == "text_extraction" || message.Type == textExtractionResultMessageType {
			hiddenThreads[message.ThreadID] = true
		}
	}
	visible := make([]design.Message, 0, len(messages))
	for _, message := range messages {
		if message.ThreadID != "" && hiddenThreads[message.ThreadID] {
			continue
		}
		visible = append(visible, message)
	}
	return visible
}

func isCanvasActionMemoryMessage(message design.Message) bool {
	return message.Name == "canvas_action" || message.ToolHint == "canvas_action"
}

func inlineInputMemory(messages []design.AgentChatMessage) string {
	var lines []string
	for _, message := range messages {
		for _, content := range message.Contents {
			switch strings.ToLower(strings.TrimSpace(content.Type)) {
			case "text":
				if strings.EqualFold(strings.TrimSpace(content.TextSource), "settings") {
					continue
				}
				if text := strings.TrimSpace(content.Text); text != "" {
					text = stripImageGeneratorDirectiveLines(text)
					if text == "" {
						continue
					}
					lines = append(lines, "- text: "+shortenMemoryText(text, 280))
				}
			case "image":
				if imageURL := strings.TrimSpace(content.ImageURL); imageURL != "" {
					size := ""
					if content.ImageWidth > 0 && content.ImageHeight > 0 {
						size = fmt.Sprintf(" (%dx%d)", content.ImageWidth, content.ImageHeight)
					}
					lines = append(lines, "- reference image"+size)
				}
			}
		}
	}
	return strings.Join(lines, "\n")
}

func recentMessageMemory(messages []design.Message, limit int) string {
	var lines []string
	start := 0
	if len(messages) > limit {
		start = len(messages) - limit
	}
	omitted := start
	for _, message := range messages[start:] {
		if message.Role == "tool" || message.Role == "error" {
			continue
		}
		content := strings.TrimSpace(message.Content)
		if content == "" {
			content = strings.TrimSpace(message.Title)
		}
		if content == "" {
			continue
		}
		lines = append(lines, fmt.Sprintf("- %s: %s", message.Role, shortenMemoryText(content, 260)))
	}
	if omitted > 0 && len(lines) > 0 {
		lines = append([]string{fmt.Sprintf("- older conversation omitted: %d messages", omitted)}, lines...)
	}
	return strings.Join(lines, "\n")
}

func canvasNodeMemory(nodes []design.Node, limit int) string {
	var candidates []design.Node
	for _, node := range nodes {
		if node.Status == "generating" || node.LayerRole == "pen-stroke" {
			continue
		}
		candidates = append(candidates, node)
	}
	if len(candidates) > limit {
		candidates = candidates[len(candidates)-limit:]
	}
	var lines []string
	for _, node := range candidates {
		content := strings.TrimSpace(node.Content)
		if isGeneratedImageContent(content) || strings.HasPrefix(content, "/canvas-assets/") || strings.HasPrefix(content, "http") {
			content = "asset reference"
		}
		if content != "" {
			content = " | " + shortenMemoryText(content, 160)
		}
		lines = append(lines, fmt.Sprintf("- %s %q at %.0f,%.0f %.0fx%.0f%s", node.Type, node.Title, node.X, node.Y, node.Width, node.Height, content))
	}
	return strings.Join(lines, "\n")
}

func completedArtifactMemory(nodes []design.Node, limit int) string {
	var lines []string
	for _, node := range nodes {
		if node.Status != "success" && node.Status != "ready" && node.Status != "" {
			continue
		}
		if node.Type != design.NodeTypeImage && node.Type != design.NodeTypeFrame && node.Type != design.NodeTypeText {
			continue
		}
		content := strings.TrimSpace(node.Content)
		if len(content) > 120 {
			content = shortenMemoryText(content, 120)
		}
		line := fmt.Sprintf("- %s: %s", node.Type, strings.TrimSpace(node.Title))
		if content != "" && (strings.HasPrefix(content, "http") || strings.HasPrefix(content, "/canvas-assets/")) {
			line += " | asset reference"
		}
		lines = append(lines, line)
	}
	if len(lines) > limit {
		lines = lines[len(lines)-limit:]
	}
	return strings.Join(lines, "\n")
}

func durableDecisionMemory(messages []design.Message, limit int) string {
	keywords := []string{
		"保留", "不要", "必须", "参考", "风格", "品牌", "颜色", "色彩", "字体", "logo", "主视觉", "电商", "官网",
		"keep", "avoid", "must", "reference", "style", "brand", "color", "typography", "logo", "hero", "ecommerce",
	}
	var lines []string
	for _, message := range messages {
		if message.Role != "user" {
			continue
		}
		content := strings.TrimSpace(message.Content)
		if content == "" || !containsAnyFold(content, keywords) {
			continue
		}
		lines = append(lines, "- "+shortenMemoryText(content, 260))
	}
	if len(lines) > limit {
		lines = lines[len(lines)-limit:]
	}
	return strings.Join(lines, "\n")
}

func researchMemory(messages []design.Message) string {
	var lines []string
	for _, message := range messages {
		if message.Role != "tool" || message.Title != "Synthesize Skills" {
			continue
		}
		var report struct {
			Query   string `json:"query"`
			Results []struct {
				Title   string `json:"title"`
				URL     string `json:"url"`
				Snippet string `json:"snippet"`
			} `json:"results"`
		}
		if err := json.Unmarshal([]byte(message.Content), &report); err != nil {
			continue
		}
		if strings.TrimSpace(report.Query) != "" {
			lines = append(lines, "- query: "+shortenMemoryText(report.Query, 160))
		}
		for _, result := range report.Results {
			title := strings.TrimSpace(result.Title)
			if title == "" {
				continue
			}
			line := "  result: " + shortenMemoryText(title, 140)
			if snippet := strings.TrimSpace(result.Snippet); snippet != "" {
				line += " | " + shortenMemoryText(snippet, 160)
			}
			lines = append(lines, line)
			if len(lines) >= 10 {
				break
			}
		}
	}
	if len(lines) > 10 {
		lines = lines[len(lines)-10:]
	}
	return strings.Join(lines, "\n")
}

func containsAnyFold(value string, keywords []string) bool {
	value = strings.ToLower(value)
	for _, keyword := range keywords {
		if strings.Contains(value, strings.ToLower(keyword)) {
			return true
		}
	}
	return false
}

func shortenMemoryText(value string, limit int) string {
	value = sanitizeMemoryText(value)
	value = strings.Join(strings.Fields(strings.TrimSpace(value)), " ")
	if limit <= 0 {
		return value
	}
	runes := []rune(value)
	if len(runes) <= limit {
		return value
	}
	return string(runes[:limit]) + "..."
}

func sanitizeMemoryText(value string) string {
	return agentMemoryURLPattern.ReplaceAllString(strings.TrimSpace(value), "[reference]")
}

func clampMemoryBlock(value string, limit int) string {
	value = strings.TrimSpace(sanitizeMemoryText(value))
	if limit <= 0 || utf8.RuneCountInString(value) <= limit {
		return value
	}
	runes := []rune(value)
	clamped := strings.TrimSpace(string(runes[:limit]))
	if cut := strings.LastIndex(clamped, "\n"); cut > limit*3/4 {
		clamped = strings.TrimSpace(clamped[:cut])
	}
	return clamped + "\n- memory window truncated; older low-signal context omitted"
}