"""
Data importer for Claude Code .claude.json file.

This module provides functionality to import historical data from the
.claude.json configuration file into the project tracker.
"""

import json
import os
from datetime import datetime, timedelta
from pathlib import Path
from typing import Dict, List, Optional, Any

from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select

from app.database.connection import get_db
from app.models.project import Project
from app.models.session import Session
from app.models.conversation import Conversation

router = APIRouter()


class ClaudeJsonImporter:
    """Importer for .claude.json data."""
    
    def __init__(self, db: AsyncSession):
        self.db = db
    
    async def import_from_file(self, file_path: str) -> Dict[str, Any]:
        """Import data from .claude.json file."""
        if not os.path.exists(file_path):
            raise FileNotFoundError(f"Claude configuration file not found: {file_path}")
        
        try:
            with open(file_path, 'r', encoding='utf-8') as f:
                claude_data = json.load(f)
        except json.JSONDecodeError as e:
            raise ValueError(f"Invalid JSON in Claude configuration file: {e}")
        
        results = {
            "projects_imported": 0,
            "sessions_estimated": 0,
            "conversations_imported": 0,
            "errors": []
        }
        
        # Import basic usage statistics
        await self._import_usage_stats(claude_data, results)
        
        # Import projects and their history
        if "projects" in claude_data:
            await self._import_projects(claude_data["projects"], results)
        
        return results
    
    async def _import_usage_stats(self, claude_data: Dict[str, Any], results: Dict[str, Any]):
        """Import basic usage statistics."""
        # We could create a synthetic "Claude Code Usage" project to track overall stats
        if claude_data.get("numStartups") and claude_data.get("firstStartTime"):
            try:
                first_start = datetime.fromisoformat(
                    claude_data["firstStartTime"].replace('Z', '+00:00')
                )
                
                # Create a synthetic project for overall Claude Code usage
                usage_project = await self._get_or_create_project(
                    name="Claude Code Usage Statistics",
                    path="<system>",
                    description="Imported usage statistics from .claude.json"
                )
                
                # Estimate session distribution over time
                num_startups = claude_data["numStartups"]
                days_since_first = (datetime.now() - first_start.replace(tzinfo=None)).days
                
                if days_since_first > 0:
                    # Create estimated sessions spread over the usage period
                    await self._create_estimated_sessions(
                        usage_project, 
                        first_start.replace(tzinfo=None), 
                        num_startups, 
                        days_since_first
                    )
                    results["sessions_estimated"] = num_startups
                
            except Exception as e:
                results["errors"].append(f"Failed to import usage stats: {e}")
    
    async def _import_projects(self, projects_data: Dict[str, Any], results: Dict[str, Any]):
        """Import project data from .claude.json."""
        for project_path, project_info in projects_data.items():
            try:
                # Skip system paths or non-meaningful paths
                if project_path in ["<system>", "/", "/tmp"]:
                    continue
                
                # Extract project name from path
                project_name = Path(project_path).name or "Unknown Project"
                
                # Create or get existing project
                project = await self._get_or_create_project(
                    name=project_name,
                    path=project_path
                )
                
                results["projects_imported"] += 1
                
                # Import conversation history if available
                if "history" in project_info and isinstance(project_info["history"], list):
                    conversation_count = await self._import_project_history(
                        project, 
                        project_info["history"]
                    )
                    results["conversations_imported"] += conversation_count
                
            except Exception as e:
                results["errors"].append(f"Failed to import project {project_path}: {e}")
    
    async def _get_or_create_project(
        self, 
        name: str, 
        path: str, 
        description: Optional[str] = None
    ) -> Project:
        """Get existing project or create new one."""
        # Check if project already exists
        result = await self.db.execute(
            select(Project).where(Project.path == path)
        )
        existing_project = result.scalars().first()
        
        if existing_project:
            return existing_project
        
        # Try to detect languages from path
        languages = self._detect_languages(path)
        
        # Create new project
        project = Project(
            name=name,
            path=path,
            languages=languages
        )
        
        self.db.add(project)
        await self.db.commit()
        await self.db.refresh(project)
        
        return project
    
    def _detect_languages(self, project_path: str) -> Optional[List[str]]:
        """Attempt to detect programming languages from project directory."""
        languages = []
        
        try:
            if os.path.exists(project_path) and os.path.isdir(project_path):
                # Look for common files to infer languages
                files = os.listdir(project_path)
                
                # Python
                if any(f.endswith(('.py', '.pyx', '.pyi')) for f in files) or 'requirements.txt' in files:
                    languages.append('python')
                
                # JavaScript/TypeScript
                if any(f.endswith(('.js', '.jsx', '.ts', '.tsx')) for f in files) or 'package.json' in files:
                    if any(f.endswith(('.ts', '.tsx')) for f in files):
                        languages.append('typescript')
                    else:
                        languages.append('javascript')
                
                # Go
                if any(f.endswith('.go') for f in files) or 'go.mod' in files:
                    languages.append('go')
                
                # Rust
                if any(f.endswith('.rs') for f in files) or 'Cargo.toml' in files:
                    languages.append('rust')
                
                # Java
                if any(f.endswith('.java') for f in files) or 'pom.xml' in files:
                    languages.append('java')
                
        except (OSError, PermissionError):
            # If we can't read the directory, that's okay
            pass
        
        return languages if languages else None
    
    async def _create_estimated_sessions(
        self, 
        project: Project, 
        first_start: datetime, 
        num_startups: int, 
        days_since_first: int
    ):
        """Create estimated sessions based on startup count."""
        # Check if we already have sessions for this project
        existing_sessions = await self.db.execute(
            select(Session).where(
                Session.project_id == project.id,
                Session.session_type == "startup"
            )
        )
        if existing_sessions.scalars().first():
            return  # Sessions already exist, skip creation
            
        # Don't create too many sessions - limit to reasonable estimates
        max_sessions = min(num_startups, 50)  # Cap at 50 sessions
        
        # Distribute sessions over the time period
        if days_since_first > 0:
            sessions_per_day = max_sessions / days_since_first
            
            for i in range(max_sessions):
                # Spread sessions over the time period
                days_offset = int(i / sessions_per_day) if sessions_per_day > 0 else i
                session_time = first_start + timedelta(days=days_offset)
                
                # Estimate session duration (30-180 minutes)
                import random
                duration = random.randint(30, 180)
                
                session = Session(
                    project_id=project.id,
                    start_time=session_time,
                    end_time=session_time + timedelta(minutes=duration),
                    session_type="startup",
                    working_directory=project.path,
                    duration_minutes=duration,
                    activity_count=random.randint(5, 25),  # Estimated activity
                    conversation_count=random.randint(2, 8)  # Estimated conversations
                )
                
                self.db.add(session)
            
            await self.db.commit()
    
    async def _import_project_history(
        self, 
        project: Project, 
        history: List[Dict[str, Any]]
    ) -> int:
        """Import conversation history for a project."""
        # Check if we already have history conversations for this project
        existing_conversations = await self.db.execute(
            select(Conversation).where(
                Conversation.context.like('%"imported_from": ".claude.json"%'),
                Conversation.session.has(Session.project_id == project.id)
            )
        )
        if existing_conversations.scalars().first():
            return 0  # History already imported, skip
        
        conversation_count = 0
        
        # Create a synthetic session for imported history
        history_session = Session(
            project_id=project.id,
            start_time=datetime.now() - timedelta(days=30),  # Assume recent
            session_type="history_import",  # Different type to avoid conflicts
            working_directory=project.path,
            activity_count=len(history),
            conversation_count=len(history)
        )
        
        self.db.add(history_session)
        await self.db.commit()
        await self.db.refresh(history_session)
        
        # Import each history entry as a conversation
        for i, entry in enumerate(history[:20]):  # Limit to 20 entries
            try:
                display_text = entry.get("display", "")
                if display_text:
                    conversation = Conversation(
                        session_id=history_session.id,
                        timestamp=history_session.start_time + timedelta(minutes=i * 5),
                        user_prompt=display_text,
                        exchange_type="user_prompt",
                        context={"imported_from": ".claude.json"}
                    )
                    
                    self.db.add(conversation)
                    conversation_count += 1
            except Exception as e:
                # Skip problematic entries
                continue
        
        if conversation_count > 0:
            await self.db.commit()
        
        return conversation_count


@router.post("/import/claude-json")
async def import_claude_json(
    file_path: Optional[str] = None,
    db: AsyncSession = Depends(get_db)
):
    """
    Import data from .claude.json file.
    
    If no file_path is provided, tries to find .claude.json in the user's home directory.
    """
    if not file_path:
        # Try default location
        home_path = Path.home() / ".claude.json"
        file_path = str(home_path)
    
    try:
        importer = ClaudeJsonImporter(db)
        results = await importer.import_from_file(file_path)
        
        return {
            "success": True,
            "message": "Import completed successfully",
            "results": results
        }
        
    except FileNotFoundError as e:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail=f"Claude configuration file not found: {e}"
        )
    except ValueError as e:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"Invalid file format: {e}"
        )
    except Exception as e:
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail=f"Import failed: {e}"
        )


@router.get("/import/claude-json/preview")
async def preview_claude_json_import(
    file_path: Optional[str] = None
):
    """
    Preview what would be imported from .claude.json file without actually importing.
    """
    if not file_path:
        home_path = Path.home() / ".claude.json"
        file_path = str(home_path)
    
    if not os.path.exists(file_path):
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail="Claude configuration file not found"
        )
    
    try:
        with open(file_path, 'r', encoding='utf-8') as f:
            claude_data = json.load(f)
    except json.JSONDecodeError as e:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"Invalid JSON in Claude configuration file: {e}"
        )
    
    preview = {
        "file_path": file_path,
        "file_size_mb": round(os.path.getsize(file_path) / (1024 * 1024), 2),
        "claude_usage": {
            "num_startups": claude_data.get("numStartups", 0),
            "first_start_time": claude_data.get("firstStartTime"),
            "prompt_queue_use_count": claude_data.get("promptQueueUseCount", 0)
        },
        "projects": {
            "total_count": len(claude_data.get("projects", {})),
            "paths": list(claude_data.get("projects", {}).keys())[:10],  # Show first 10
            "has_more": len(claude_data.get("projects", {})) > 10
        },
        "history_entries": 0
    }
    
    # Count total history entries across all projects
    if "projects" in claude_data:
        total_history = sum(
            len(proj.get("history", [])) 
            for proj in claude_data["projects"].values()
        )
        preview["history_entries"] = total_history
    
    return preview