app.py

import streamlit as st
import subprocess
import pandas as pd
import os

st.set_page_config(page_title="Cache Simulator Dashboard", layout="wide")

st.title("🚀 CS204 Cache Simulator Dashboard")
st.markdown("Interactive frontend for the C++ Cache Simulator")

# --- UI CONTROLS (Sidebar) ---
st.sidebar.header("Simulation Parameters")

trace_file = st.sidebar.text_input("Trace File", value="cds.txt")
policy = st.sidebar.selectbox("Replacement Policy", ["LRU", "FIFO", "LFU", "RANDOM", "OPT"])

# Slider inputs for cache architecture
sets = st.sidebar.select_slider("Number of Sets (Power of 2)", options=[16, 32, 64, 128, 256, 512, 1024, 2048], value=128)
assoc = st.sidebar.select_slider("Associativity (Ways)", options=[1, 2, 4, 8, 16], value=4)
line = st.sidebar.select_slider("Line Size (Bytes)", options=[16, 32, 64, 128], value=64)

# Automatically calculate size in KB to satisfy the C++ constraint
size_kb = (sets * assoc * line) // 1024
st.sidebar.info(f"**Calculated Cache Size:** {size_kb} KB")

# Output heatmap CSV name
csv_out = f"{policy}_heatmap.csv"

# --- RUN SIMULATION ---
if st.sidebar.button("Run Simulation", type="primary"):
    if size_kb == 0:
        st.error("Cache size must be at least 1 KB. Please increase Sets, Assoc, or Line Size.")
    else:
        with st.spinner(f"Running C++ Simulator for {policy}..."):
            # Construct the CLI command
            cmd = [
                "./cache_sim",
                "--trace", trace_file,
                "--size", str(size_kb),
                "--sets", str(sets),
                "--assoc", str(assoc),
                "--line", str(line),
                "--policy", policy,
                "--heatmap", csv_out
            ]
            
            try:
                # Execute the C++ binary
                result = subprocess.run(cmd, capture_output=True, text=True, check=True)
                
                # Check if the CSV was created
                if os.path.exists(csv_out):
                    st.success("Simulation Complete!")
                    
                    # Read the generated CSV
                    df = pd.read_csv(csv_out)
                    df.set_index("set_id", inplace=True)
                    
                    # --- DASHBOARD METRICS ---
                    st.subheader(f"Results for {policy} Policy")
                    total_evictions = df["evictions"].sum()
                    avg_hit_rate = df["hit_rate"].mean()
                    hottest_set = df["evictions"].idxmax()
                    
                    col1, col2, col3 = st.columns(3)
                    col1.metric("Total Evictions", f"{total_evictions:,}")
                    col2.metric("Average Hit Rate", f"{avg_hit_rate:.2f}%")
                    col3.metric("Hottest Set", f"Set {hottest_set}")
                    
                    # --- INTERACTIVE CHARTS ---
                    st.markdown("### Evictions per Set")
                    # Streamlit's native bar chart (interactive, hoverable)
                    st.bar_chart(df["evictions"], color="#ff4b4b")
                    
                    st.markdown("### Hit Rate per Set (%)")
                    st.line_chart(df["hit_rate"], color="#00ff00")
                    
                else:
                    st.error("Simulation ran, but no heatmap CSV was found.")
                    st.text("C++ Output:\n" + result.stderr)
                    
            except subprocess.CalledProcessError as e:
                st.error("Error running the simulator. Check your parameters or trace file.")
                st.text(e.stderr)