import difflib
import html
import tempfile
import json
import os

def generate_html_diff(old_text: str, new_text: str) -> str:
    """
    Compares original prompt with optimized prompt.
    Returns a beautifully styled HTML block mimicking GitHub's code diff view.
    """
    if not old_text.strip():
        return "<p style='color: #64748b;'>Enter a prompt to compare changes.</p>"
        
    old_lines = old_text.splitlines()
    new_lines = new_text.splitlines()
    
    diff = list(difflib.ndiff(old_lines, new_lines))
    
    html_out = [
        '<div style="font-family: \'Fira Code\', Consolas, Monaco, monospace; font-size: 13px; line-height: 1.6; '
        'background-color: #0b0f19; border: 1px solid #1e293b; padding: 16px; border-radius: 8px; overflow-x: auto; color: #cbd5e1;">'
    ]
    
    for idx, line in enumerate(diff):
        if line.startswith('+ '):
            content = html.escape(line[2:])
            html_out.append(
                f'<div style="background-color: rgba(16, 185, 129, 0.1); color: #34d399; padding: 2px 8px; '
                f'border-left: 3px solid #10b981; white-space: pre-wrap; margin: 1px 0;"><span style="user-select: none; color: #059669; margin-right: 12px;">+</span>{content}</div>'
            )
        elif line.startswith('- '):
            content = html.escape(line[2:])
            html_out.append(
                f'<div style="background-color: rgba(239, 68, 68, 0.1); color: #f87171; padding: 2px 8px; '
                f'border-left: 3px solid #ef4444; white-space: pre-wrap; margin: 1px 0; text-decoration: line-through;"><span style="user-select: none; color: #dc2626; margin-right: 12px;">-</span>{content}</div>'
            )
        elif line.startswith('  '):
            content = html.escape(line[2:])
            html_out.append(
                f'<div style="padding: 2px 8px; white-space: pre-wrap; margin: 1px 0; color: #94a3b8;"><span style="user-select: none; color: #475569; margin-right: 12px;"> </span>{content}</div>'
            )
        # We ignore '? ' line details to keep clean visual aesthetics
        
    html_out.append('</div>')
    return "\n".join(html_out)

def estimate_tokens(text: str) -> dict:
    """
    Returns an estimation dictionary containing word count, character count,
    and estimated LLM tokens (approx 1 token per 4 characters).
    """
    chars = len(text)
    words = len(text.split())
    tokens = max(0, round(chars / 4.0))
    return {
        "characters": chars,
        "words": words,
        "tokens": tokens
    }

import uuid

def create_export_file(prompt_text: str, format_type: str) -> str:
    """
    Saves the prompt into a temporary file of the selected format
    and returns the file path for Gradio download.
    """
    # Create temporary files under a unique name to ensure multi-user safety
    temp_dir = tempfile.gettempdir()
    unique_id = uuid.uuid4().hex[:8]
    
    if format_type.lower() == "markdown":
        file_path = os.path.join(temp_dir, f"promptlab_export_{unique_id}.md")
        with open(file_path, "w", encoding="utf-8") as f:
            f.write(f"# Optimized Prompt\n\nGenerated by PromptLab\n\n```markdown\n{prompt_text}\n```\n")
            
    elif format_type.lower() == "json":
        file_path = os.path.join(temp_dir, f"promptlab_export_{unique_id}.json")
        with open(file_path, "w", encoding="utf-8") as f:
            json.dump({
                "source": "PromptLab",
                "optimized_prompt": prompt_text
            }, f, indent=2)
            
    else:  # TXT default
        file_path = os.path.join(temp_dir, f"promptlab_export_{unique_id}.txt")
        with open(file_path, "w", encoding="utf-8") as f:
            f.write(prompt_text)
            
    return file_path