import gradio as gr

# -------------------------------
# Knowledge Base
# -------------------------------
facts = []
rules = []

# -------------------------------
# Functions
# -------------------------------

def add_fact(fact):
    fact = fact.strip()
    if fact:
        facts.append(fact)
        return f"✅ Fact added: {fact}"
    return "⚠️ Please enter a valid fact"

def add_rule(rule):
    rule = rule.strip()
    if rule:
        rules.append(rule)
        return f"✅ Rule added: {rule}"
    return "⚠️ Please enter a valid rule"

def infer(query):
    query = query.strip()
    
    # Direct fact check
    if query in facts:
        return "✅ TRUE (Found in facts)"
    
    # Rule-based inference
    for rule in rules:
        if "->" in rule:
            left, right = rule.split("->")
            left = left.strip()
            right = right.strip()
            
            for fact in facts:
                if "(" in fact:
                    name = fact.split("(")[1].replace(")", "")
                    
                    if left.replace("x", name) == fact:
                        if right.replace("x", name) == query:
                            return "✅ TRUE (Derived using rule)"
    
    return "❌ FALSE (Not proven)"

# -------------------------------
# UI Functions
# -------------------------------

def ui_add_fact(fact):
    return add_fact(fact)

def ui_add_rule(rule):
    return add_rule(rule)

def ui_query(query):
    return infer(query)

# -------------------------------
# Gradio UI (HCI Friendly)
# -------------------------------

with gr.Blocks(theme=gr.themes.Soft()) as app:
    
    gr.Markdown("# 🧠 Predicate Logic Simulator")
    gr.Markdown("Add facts, rules, and test queries easily")
    
    with gr.Tab("➕ Add Fact"):
        fact_input = gr.Textbox(label="Enter Fact (e.g., Human(Socrates))")
        fact_output = gr.Textbox(label="Output")
        fact_btn = gr.Button("Add Fact")
        fact_btn.click(ui_add_fact, inputs=fact_input, outputs=fact_output)
    
    with gr.Tab("📜 Add Rule"):
        rule_input = gr.Textbox(label="Enter Rule (e.g., Human(x) -> Mortal(x))")
        rule_output = gr.Textbox(label="Output")
        rule_btn = gr.Button("Add Rule")
        rule_btn.click(ui_add_rule, inputs=rule_input, outputs=rule_output)
    
    with gr.Tab("🔍 Query"):
        query_input = gr.Textbox(label="Enter Query (e.g., Mortal(Socrates))")
        query_output = gr.Textbox(label="Result")
        query_btn = gr.Button("Check")
        query_btn.click(ui_query, inputs=query_input, outputs=query_output)

# -------------------------------
# Launch App
# -------------------------------
app.launch()