app.py

import os
import gradio as gr
from langchain.chat_models import ChatOpenAI
from langchain.prompts import ChatPromptTemplate
from langchain.chains import LLMChain, SequentialChain
from langchain.memory import ConversationBufferMemory
import random

# Global variables
current_story = ""
story_branches = {}
story_history = []

def generate_story_idea(llm, genre, theme, length):
    """Generate a story idea based on user inputs"""
    idea_prompt = ChatPromptTemplate.from_template(
        """You are a creative writing assistant.
        Generate a compelling story idea for a {length} story in the {genre} genre 
        that explores the theme of {theme}.
        Include a brief plot outline, main character, and setting.
        Respond with just the idea, no additional commentary.
        """
    )
    
    idea_chain = LLMChain(llm=llm, prompt=idea_prompt, output_key="story_idea")
    return idea_chain.run(genre=genre, theme=theme, length=length)

def create_story_beginning(llm, story_idea):
    """Create the beginning of a story based on the idea"""
    beginning_prompt = ChatPromptTemplate.from_template(
        """You are a creative writing assistant.
        Based on this story idea: {story_idea}
        
        Write an engaging opening for this story that introduces the main character and setting.
        Make it compelling and hook the reader immediately.
        Write approximately 250-350 words.
        """
    )
    
    beginning_chain = LLMChain(llm=llm, prompt=beginning_prompt, output_key="story_beginning")
    return beginning_chain.run(story_idea=story_idea)

def continue_linear_story(llm, story_so_far):
    """Continue a linear story based on the story so far"""
    continue_prompt = ChatPromptTemplate.from_template(
        """You are a creative writing assistant.
        Continue this story:
        
        {story_so_far}
        
        Write the next part of the story (approximately 250-350 words), advancing the plot in an interesting way.
        End at a point that feels satisfying but leaves room for more story.
        """
    )
    
    continue_chain = LLMChain(llm=llm, prompt=continue_prompt, output_key="story_continuation")
    return continue_chain.run(story_so_far=story_so_far)

def generate_story_branches(llm, story_so_far):
    """Generate three possible story continuations as branches"""
    branch_prompt = ChatPromptTemplate.from_template(
        """You are a creative writing assistant.
        Based on this story so far:
        
        {story_so_far}
        
        Generate THREE possible directions the story could take next. For each:
        1. Provide a brief title (10 words or less)
        2. Write a short description (1-2 sentences)
        
        Format as:
        Option 1: [Title]
        [Description]
        
        Option 2: [Title]
        [Description]
        
        Option 3: [Title]
        [Description]
        """
    )
    
    branch_chain = LLMChain(llm=llm, prompt=branch_prompt, output_key="story_branches")
    branches_text = branch_chain.run(story_so_far=story_so_far)
    
    # Parse the branches
    branches = []
    lines = branches_text.strip().split('\n')
    current_option = None
    current_description = ""
    
    for line in lines:
        if line.startswith("Option "):
            if current_option:
                branches.append((current_option, current_description.strip()))
            current_option = line.split(": ", 1)[1] if ": " in line else line
            current_description = ""
        elif current_option is not None:
            current_description += line + " "
    
    if current_option:
        branches.append((current_option, current_description.strip()))
    
    return branches

def continue_branch(llm, story_so_far, branch_title, branch_description):
    """Continue the story based on the selected branch"""
    branch_continue_prompt = ChatPromptTemplate.from_template(
        """You are a creative writing assistant.
        Continue this story:
        
        {story_so_far}
        
        The story should now follow this direction:
        {branch_title} - {branch_description}
        
        Write the next part of the story (approximately 250-350 words) following this direction.
        Make it engaging and consistent with what came before.
        """
    )
    
    branch_chain = LLMChain(llm=llm, prompt=branch_continue_prompt, output_key="branch_continuation")
    return branch_chain.run(
        story_so_far=story_so_far, 
        branch_title=branch_title, 
        branch_description=branch_description
    )

def initialize_story(api_key, genre, theme, length):
    """Initialize a new story with the given parameters"""
    global current_story, story_branches, story_history
    
    try:
        # Initialize LLM
        llm = ChatOpenAI(
            openai_api_key=api_key,
            model="gpt-4.5-preview",
            temperature=0.7
        )
        
        # Reset story state
        current_story = ""
        story_branches = {}
        story_history = []
        
        # Generate story idea and beginning
        story_idea = generate_story_idea(llm, genre, theme, length)
        story_beginning = create_story_beginning(llm, story_idea)
        
        current_story = story_beginning
        story_history.append(current_story)
        
        # Return the story beginning and available actions
        return (
            f"Story Idea:\n{story_idea}\n\n" + 
            f"Story Beginning:\n{story_beginning}", 
            gr.update(visible=True), 
            gr.update(visible=True),
            gr.update(visible=True)
        )
    except Exception as e:
        return f"Error initializing story: {str(e)}", gr.update(visible=False), gr.update(visible=False), gr.update(visible=False)

def continue_story(api_key):
    """Continue the linear story"""
    global current_story, story_history
    
    try:
        # Initialize LLM
        llm = ChatOpenAI(
            openai_api_key=api_key,
            model="gpt-4.5-preview",
            temperature=0.7
        )
        
        # Continue the story
        continuation = continue_linear_story(llm, current_story)
        current_story += "\n\n" + continuation
        story_history.append(continuation)
        
        return current_story, gr.update(value="Story continued successfully!")
    except Exception as e:
        return current_story, gr.update(value=f"Error continuing story: {str(e)}")

def generate_branches(api_key):
    """Generate branching options for the story"""
    global current_story, story_branches
    
    try:
        # Initialize LLM
        llm = ChatOpenAI(
            openai_api_key=api_key,
            model="gpt-4.5-preview",
            temperature=0.8  # Higher temperature for more creative branches
        )
        
        # Generate branches
        branches = generate_story_branches(llm, current_story)
        story_branches = {f"Option {i+1}: {title}": (title, desc) for i, (title, desc) in enumerate(branches)}
        
        # Create formatted output for display
        branches_output = "\n\n".join([f"{option}\n{desc}" for option, (_, desc) in story_branches.items()])
        
        # Create radio options
        radio_options = list(story_branches.keys())
        
        return branches_output, gr.update(choices=radio_options, value=radio_options[0] if radio_options else None, visible=True), gr.update(visible=True)
    except Exception as e:
        return f"Error generating branches: {str(e)}", gr.update(visible=False), gr.update(visible=False)

def select_branch(api_key, selected_branch):
    """Continue the story based on the selected branch"""
    global current_story, story_branches, story_history
    
    try:
        if not selected_branch or selected_branch not in story_branches:
            return current_story, "Please select a valid branch."
        
        # Initialize LLM
        llm = ChatOpenAI(
            openai_api_key=api_key,
            model="gpt-4-turbo",
            temperature=0.7
        )
        
        # Get branch details
        branch_title, branch_description = story_branches[selected_branch]
        
        # Continue along the selected branch
        continuation = continue_branch(llm, current_story, branch_title, branch_description)
        
        # Update story state
        current_story += f"\n\n[{selected_branch}]\n\n" + continuation
        story_history.append(f"[Branch: {branch_title}] {continuation}")
        
        return current_story, gr.update(value="Branch selected and story continued!")
    except Exception as e:
        return current_story, gr.update(value=f"Error selecting branch: {str(e)}")

def create_app():
    """Create the Gradio interface"""
    with gr.Blocks(title="AI Story Generator", theme=gr.themes.Soft()) as app:
        gr.Markdown("# 📚 AI-Powered Story Generator")
        gr.Markdown("Create interactive stories with branching narratives using OpenAI and LangChain")
        
        with gr.Row():
            with gr.Column(scale=1):
                api_key = gr.Textbox(
                    label="OpenAI API Key", 
                    placeholder="Enter your OpenAI API key here", 
                    type="password"
                )
                
                with gr.Group():
                    gr.Markdown("### Story Parameters")
                    genre = gr.Dropdown(
                        label="Genre",
                        choices=[
                            "Fantasy", "Science Fiction", "Mystery", "Romance", 
                            "Horror", "Adventure", "Historical Fiction", "Comedy"
                        ],
                        value="Fantasy"
                    )
                    theme = gr.Textbox(
                        label="Theme", 
                        placeholder="e.g., Redemption, Loss, Discovery" 
                        # value="Adventure"
                    )
                    length = gr.Radio(
                        label="Story Length", 
                        choices=["Short Story", "Novella", "Novel Chapter"],
                        value="Short Story"
                    )
                
                with gr.Row():
                    start_btn = gr.Button("Start New Story", variant="primary")
                
                with gr.Row():
                    continue_btn = gr.Button("Continue Story", visible=False)
                    branch_btn = gr.Button("Generate Branch Options", visible=False)
                
                status = gr.Textbox(label="Status", value="", visible=True)
                
                with gr.Group(visible=False) as branch_group:
                    branch_output = gr.Textbox(label="Story Branches")
                    branch_selection = gr.Radio(label="Select a Branch", choices=[])
                    select_branch_btn = gr.Button("Continue with Selected Branch")
            
            with gr.Column(scale=2):
                story_output = gr.Textbox(
                    label="Generated Story", 
                    placeholder="Your story will appear here...",
                    lines=20
                )
        
        # Define button click events
        start_btn.click(
            initialize_story,
            inputs=[api_key, genre, theme, length],
            outputs=[story_output, continue_btn, branch_btn, branch_group]
        )
        
        continue_btn.click(
            continue_story,
            inputs=[api_key],
            outputs=[story_output, status]
        )
        
        branch_btn.click(
            generate_branches,
            inputs=[api_key],
            outputs=[branch_output, branch_selection, select_branch_btn]
        )
        
        select_branch_btn.click(
            select_branch,
            inputs=[api_key, branch_selection],
            outputs=[story_output, status]
        )
        
        # Example usage
        gr.Examples(
            examples=[
                ["Fantasy", "Coming of age", "Short Story"],
                ["Science Fiction", "Artificial intelligence", "Novella"],
                ["Mystery", "Betrayal", "Novel Chapter"]
            ],
            inputs=[genre, theme, length],
            outputs=[]
        )
        
        gr.Markdown("""
        ## How to Use
        1. Enter your OpenAI API key
        2. Select a genre, theme, and length
        3. Click "Start New Story" to begin
        4. Continue the linear story or generate branching options
        5. If you chose branching, select a branch to follow
        
        This app uses LangChain to orchestrate the story generation process and OpenAI's models to create the content.
        """)
    
    return app

if __name__ == "__main__":
    app = create_app()
    app.launch()