package agent

import (
	"encoding/base64"
	"fmt"
	"mime"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"time"

	"clawgo/pkg/config"
	"clawgo/pkg/logger"
	"clawgo/pkg/providers"
	"clawgo/pkg/skills"
)

type ContextBuilder struct {
	workspace    string
	skillsLoader *skills.SkillsLoader
	memory       *MemoryStore
	toolsSummary func() []string // Function to get tool summaries dynamically
}

const (
	maxInlineMediaFileBytes  int64 = 5 * 1024 * 1024
	maxInlineMediaTotalBytes int64 = 12 * 1024 * 1024
)

func getGlobalConfigDir() string {
	home, err := os.UserHomeDir()
	if err != nil {
		return ""
	}
	return filepath.Join(home, ".clawgo")
}

func NewContextBuilder(workspace string, memCfg config.MemoryConfig, toolsSummaryFunc func() []string) *ContextBuilder {
	// Built-in skills: the current project's skills directory.
	// Use the skills/ directory under the current working directory.
	wd, _ := os.Getwd()
	builtinSkillsDir := filepath.Join(wd, "skills")
	globalSkillsDir := filepath.Join(getGlobalConfigDir(), "skills")

	return &ContextBuilder{
		workspace:    workspace,
		skillsLoader: skills.NewSkillsLoader(workspace, globalSkillsDir, builtinSkillsDir),
		memory:       NewMemoryStore(workspace, memCfg),
		toolsSummary: toolsSummaryFunc,
	}
}

func (cb *ContextBuilder) getIdentity() string {
	now := time.Now().Format("2006-01-02 15:04 (Monday)")
	workspacePath, _ := filepath.Abs(filepath.Join(cb.workspace))
	runtime := fmt.Sprintf("%s %s, Go %s", runtime.GOOS, runtime.GOARCH, runtime.Version())

	// Build tools section dynamically
	toolsSection := cb.buildToolsSection()

	return fmt.Sprintf(`# clawgo 🦞

You are clawgo, a helpful AI assistant.

## Current Time
%s

## Runtime
%s

## Workspace
Your workspace is at: %s
- Memory: %s/memory/MEMORY.md
- Daily Notes: %s/memory/YYYYMM/YYYYMMDD.md
- Skills: %s/skills/{skill-name}/SKILL.md

%s

Always be helpful, accurate, and concise. When using tools, explain what you're doing.
For operational tasks (for example configuring git remotes/credentials), prefer executing tools directly instead of only giving manual steps.
If user provides credentials/tokens for a requested operation, you may use them to execute the task, but never expose full secrets in visible output.
When remembering something, write to %s/memory/MEMORY.md`,
		now, runtime, workspacePath, workspacePath, workspacePath, workspacePath, toolsSection, workspacePath)
}

func (cb *ContextBuilder) buildToolsSection() string {
	if cb.toolsSummary == nil {
		return ""
	}

	summaries := cb.toolsSummary()
	if len(summaries) == 0 {
		return ""
	}

	var sb strings.Builder
	sb.WriteString("## Available Tools\n\n")
	sb.WriteString("You have access to the following tools:\n\n")
	for _, s := range summaries {
		sb.WriteString(s)
		sb.WriteString("\n")
	}

	return sb.String()
}

func (cb *ContextBuilder) BuildSystemPrompt() string {
	parts := []string{}

	// Core identity section
	parts = append(parts, cb.getIdentity())

	// Bootstrap files
	bootstrapContent := cb.LoadBootstrapFiles()
	if bootstrapContent != "" {
		parts = append(parts, bootstrapContent)
	}

	// Skills - show summary, AI can read full content with read_file tool
	skillsSummary := cb.skillsLoader.BuildSkillsSummary()
	if skillsSummary != "" {
		parts = append(parts, fmt.Sprintf(`# Skills

The following skills extend your capabilities. To use a skill, read its SKILL.md file using the read_file tool.

%s`, skillsSummary))
	}

	// Memory context
	memoryContext := cb.memory.GetMemoryContext()
	if memoryContext != "" {
		parts = append(parts, "# Memory\n\n"+memoryContext)
	}

	// Join with "---" separator
	return strings.Join(parts, "\n\n---\n\n")
}

func (cb *ContextBuilder) LoadBootstrapFiles() string {
	bootstrapFiles := []string{
		"AGENTS.md",
		"SOUL.md",
		"USER.md",
		"IDENTITY.md",
	}

	var result string
	for _, filename := range bootstrapFiles {
		filePath := filepath.Join(cb.workspace, filename)
		if data, err := os.ReadFile(filePath); err == nil {
			result += fmt.Sprintf("## %s\n\n%s\n\n", filename, string(data))
		}
	}

	return result
}

func (cb *ContextBuilder) BuildMessages(history []providers.Message, summary string, currentMessage string, media []string, channel, chatID string) []providers.Message {
	messages := []providers.Message{}

	systemPrompt := cb.BuildSystemPrompt()

	// Add Current Session info if provided
	if channel != "" && chatID != "" {
		systemPrompt += fmt.Sprintf("\n\n## Current Session\nChannel: %s\nChat ID: %s", channel, chatID)
	}

	// Log system prompt summary for debugging (debug mode only)
	logger.DebugCF("agent", "System prompt built",
		map[string]interface{}{
			"total_chars":   len(systemPrompt),
			"total_lines":   strings.Count(systemPrompt, "\n") + 1,
			"section_count": strings.Count(systemPrompt, "\n\n---\n\n") + 1,
		})

	// Log preview of system prompt (avoid logging huge content)
	preview := systemPrompt
	if len(preview) > 500 {
		preview = preview[:500] + "... (truncated)"
	}
	logger.DebugCF("agent", "System prompt preview",
		map[string]interface{}{
			logger.FieldPreview: preview,
		})

	if summary != "" {
		systemPrompt += "\n\n## Summary of Previous Conversation\n\n" + summary
	}

	messages = append(messages, providers.Message{
		Role:    "system",
		Content: systemPrompt,
	})

	messages = append(messages, history...)

	userMsg := providers.Message{
		Role:    "user",
		Content: currentMessage,
	}
	if len(media) > 0 {
		userMsg.ContentParts = buildUserContentParts(currentMessage, media)
	}
	messages = append(messages, userMsg)

	return messages
}

func (cb *ContextBuilder) AddToolResult(messages []providers.Message, toolCallID, toolName, result string) []providers.Message {
	messages = append(messages, providers.Message{
		Role:       "tool",
		Content:    result,
		ToolCallID: toolCallID,
	})
	return messages
}

func (cb *ContextBuilder) AddAssistantMessage(messages []providers.Message, content string, toolCalls []map[string]interface{}) []providers.Message {
	msg := providers.Message{
		Role:    "assistant",
		Content: content,
	}
	// Always add assistant message, whether or not it has tool calls
	messages = append(messages, msg)
	return messages
}

func (cb *ContextBuilder) loadSkills() string {
	allSkills := cb.skillsLoader.ListSkills()
	if len(allSkills) == 0 {
		return ""
	}

	var skillNames []string
	for _, s := range allSkills {
		skillNames = append(skillNames, s.Name)
	}

	content := cb.skillsLoader.LoadSkillsForContext(skillNames)
	if content == "" {
		return ""
	}

	return "# Skill Definitions\n\n" + content
}

// GetSkillsInfo returns information about loaded skills.
func (cb *ContextBuilder) GetSkillsInfo() map[string]interface{} {
	allSkills := cb.skillsLoader.ListSkills()
	skillNames := make([]string, 0, len(allSkills))
	for _, s := range allSkills {
		skillNames = append(skillNames, s.Name)
	}
	return map[string]interface{}{
		"total":     len(allSkills),
		"available": len(allSkills),
		"names":     skillNames,
	}
}

func buildUserContentParts(text string, media []string) []providers.MessageContentPart {
	parts := make([]providers.MessageContentPart, 0, 1+len(media))
	notes := make([]string, 0)
	var totalInlineBytes int64

	if strings.TrimSpace(text) != "" {
		parts = append(parts, providers.MessageContentPart{
			Type: "input_text",
			Text: text,
		})
	}
	for _, mediaPath := range media {
		p := strings.TrimSpace(mediaPath)
		if p == "" {
			continue
		}
		if strings.HasPrefix(strings.ToLower(p), "http://") || strings.HasPrefix(strings.ToLower(p), "https://") {
			notes = append(notes, fmt.Sprintf("Attachment kept as URL only and not inlined: %s", p))
			continue
		}

		dataURL, mimeType, filename, sizeBytes, ok := buildFileDataURL(p)
		if !ok {
			notes = append(notes, fmt.Sprintf("Attachment could not be read and was skipped: %s", p))
			continue
		}
		if sizeBytes > maxInlineMediaFileBytes {
			notes = append(notes, fmt.Sprintf("Attachment too large and was not inlined (%s, %d bytes > %d bytes).", filename, sizeBytes, maxInlineMediaFileBytes))
			continue
		}
		if totalInlineBytes+sizeBytes > maxInlineMediaTotalBytes {
			notes = append(notes, fmt.Sprintf("Attachment skipped to keep request size bounded (%s).", filename))
			continue
		}
		totalInlineBytes += sizeBytes

		if strings.HasPrefix(mimeType, "image/") {
			parts = append(parts, providers.MessageContentPart{
				Type:     "input_image",
				ImageURL: dataURL,
				MIMEType: mimeType,
				Filename: filename,
			})
			continue
		}
		parts = append(parts, providers.MessageContentPart{
			Type:     "input_file",
			FileData: dataURL,
			MIMEType: mimeType,
			Filename: filename,
		})
	}

	if len(notes) > 0 {
		parts = append(parts, providers.MessageContentPart{
			Type: "input_text",
			Text: "Attachment handling notes:\n- " + strings.Join(notes, "\n- "),
		})
	}
	return parts
}

func buildFileDataURL(path string) (dataURL, mimeType, filename string, sizeBytes int64, ok bool) {
	stat, err := os.Stat(path)
	if err != nil || stat.IsDir() {
		return "", "", "", 0, false
	}

	content, err := os.ReadFile(path)
	if err != nil {
		return "", "", "", 0, false
	}
	if len(content) == 0 {
		return "", "", "", 0, false
	}
	filename = filepath.Base(path)
	mimeType = detectMIMEType(path)
	encoded := base64.StdEncoding.EncodeToString(content)
	return fmt.Sprintf("data:%s;base64,%s", mimeType, encoded), mimeType, filename, stat.Size(), true
}

func detectMIMEType(path string) string {
	ext := strings.ToLower(filepath.Ext(path))
	mimeType := mime.TypeByExtension(ext)
	if mimeType == "" {
		switch ext {
		case ".pdf":
			mimeType = "application/pdf"
		case ".doc":
			mimeType = "application/msword"
		case ".docx":
			mimeType = "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
		case ".ppt":
			mimeType = "application/vnd.ms-powerpoint"
		case ".pptx":
			mimeType = "application/vnd.openxmlformats-officedocument.presentationml.presentation"
		case ".xls":
			mimeType = "application/vnd.ms-excel"
		case ".xlsx":
			mimeType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
		}
	}
	if mimeType == "" {
		mimeType = "application/octet-stream"
	}
	return mimeType
}