Create app.py

app.py

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+import streamlit as st
+import openai
+import os
+import re
+import json
+
+# ── Page config ────────────────────────────────────────────────────────────────
+st.set_page_config(
+    page_title="CodeShift · AI Code Converter",
+    page_icon="⚡",
+    layout="wide",
+)
+
+# ── Styling ────────────────────────────────────────────────────────────────────
+st.markdown("""
+<style>
+@import url('https://fonts.googleapis.com/css2?family=JetBrains+Mono:wght@400;600&family=Syne:wght@700;800&display=swap');
+
+html, body, [class*="css"] { font-family: 'Syne', sans-serif; }
+
+.header {
+    background: linear-gradient(135deg, #1a1040, #0d1a2a);
+    padding: 24px 32px;
+    border-radius: 12px;
+    margin-bottom: 24px;
+}
+.header h1 {
+    font-size: 2rem; font-weight: 800; margin: 0;
+    background: linear-gradient(90deg, #7c6af7, #3ecfcf);
+    -webkit-background-clip: text; -webkit-text-fill-color: transparent;
+}
+.header p { color: #7a7f94; margin: 4px 0 0; font-size: 0.9rem; }
+
+.status-box { padding: 10px 16px; border-radius: 8px; font-size: 0.88rem; margin-top: 8px; }
+.status-ok   { background: #0d2b1f; border-left: 3px solid #3ecf8e; color: #3ecf8e; }
+.status-err  { background: #2b0d0d; border-left: 3px solid #f76464; color: #f76464; }
+.status-info { background: #1a1a2e; border-left: 3px solid #7c6af7; color: #a99ff7; }
+
+textarea { font-family: 'JetBrains Mono', monospace !important; font-size: 0.82rem !important; }
+</style>
+""", unsafe_allow_html=True)
+
+# ── OpenAI client ──────────────────────────────────────────────────────────────
+client = openai.OpenAI(api_key=os.environ.get("OPENAI_API_KEY"))
+
+LANGUAGES = [
+    "Python", "JavaScript", "TypeScript", "Java", "C", "C++", "C#",
+    "Go", "Rust", "Ruby", "PHP", "Swift", "Kotlin", "Bash/Shell", "SQL",
+]
+
+# ── AI helpers ─────────────────────────────────────────────────────────────────
+
+def validate_language(code: str, selected: str):
+    resp = client.chat.completions.create(
+        model="gpt-4o", temperature=0,
+        messages=[
+            {"role": "system", "content": 'Detect the programming language. Reply ONLY with JSON: {"language":"X","confidence":"high/medium/low","reason":"..."}'},
+            {"role": "user",   "content": code[:3000]},
+        ],
+    )
+    raw  = re.sub(r"```[a-z]*\n?|```", "", resp.choices[0].message.content).strip()
+    data = json.loads(raw)
+    detected = data.get("language", "Unknown")
+    match    = detected.lower() == selected.lower()
+    return detected, data.get("confidence", "?"), data.get("reason", ""), match
+
+
+def convert_code(code: str, src: str, tgt: str, notes: str):
+    prompt = (
+        f"Convert the {src} code to idiomatic {tgt}. "
+        f"Preserve all logic. Add comments for non-obvious parts. "
+        f"Return ONLY raw code — no markdown fences, no preamble."
+        + (f" Style notes: {notes}" if notes.strip() else "")
+    )
+    resp = client.chat.completions.create(
+        model="gpt-4o", temperature=0.2,
+        messages=[
+            {"role": "system", "content": prompt},
+            {"role": "user",   "content": code},
+        ],
+    )
+    return re.sub(r"```[a-z]*\n?|```", "", resp.choices[0].message.content).strip()
+
+
+def explain_code(code: str, lang: str):
+    resp = client.chat.completions.create(
+        model="gpt-4o", temperature=0.3,
+        messages=[
+            {"role": "system", "content": "Explain this code clearly in plain English using bullet points. Be concise."},
+            {"role": "user",   "content": f"{lang} code:\n\n{code[:4000]}"},
+        ],
+    )
+    return resp.choices[0].message.content.strip()
+
+# ── Header ─────────────────────────────────────────────────────────────────────
+st.markdown("""
+<div class="header">
+  <h1>⚡ CodeShift</h1>
+  <p>AI-powered code converter &amp; analyser · GPT-4o</p>
+</div>
+""", unsafe_allow_html=True)
+
+# ── Tabs ───────────────────────────────────────────────────────────────────────
+tab1, tab2, tab3 = st.tabs(["🔄 Convert", "💡 Explain", "🔎 Detect"])
+
+# ════════════════════════
+# TAB 1 — CONVERT
+# ════════════════════════
+with tab1:
+    col_l, col_r = st.columns(2, gap="medium")
+
+    with col_l:
+        st.markdown("### Source Code")
+        src_lang    = st.selectbox("Source Language", LANGUAGES, index=0, key="src_lang")
+        src_code    = st.text_area("", height=380, placeholder="# Paste your source code here…", key="src_code")
+        style_notes = st.text_input("Style notes (optional)", placeholder="e.g. 'use async/await', 'add type hints'…")
+
+        c1, c2, c3 = st.columns(3)
+        validate_btn = c1.button("🔍 Validate",  use_container_width=True)
+        convert_btn  = c2.button("⚡ Convert",   use_container_width=True, type="primary")
+        clear_btn    = c3.button("🗑 Clear",      use_container_width=True)
+
+        if validate_btn:
+            if not src_code.strip():
+                st.markdown('<div class="status-box status-info">⚪ Paste some code first.</div>', unsafe_allow_html=True)
+            else:
+                with st.spinner("Detecting language…"):
+                    detected, conf, reason, match = validate_language(src_code, src_lang)
+                if match:
+                    st.markdown(f'<div class="status-box status-ok">✅ Detected <b>{detected}</b> — matches your selection! (Confidence: {conf})<br><small>{reason}</small></div>', unsafe_allow_html=True)
+                else:
+                    st.markdown(f'<div class="status-box status-err">❌ Detected <b>{detected}</b> but you selected <b>{src_lang}</b> (Confidence: {conf})<br><small>{reason}</small></div>', unsafe_allow_html=True)
+
+        if clear_btn:
+            st.session_state["src_code"] = ""
+            st.session_state["converted"] = ""
+            st.rerun()
+
+    with col_r:
+        st.markdown("### Converted Code")
+        tgt_lang = st.selectbox("Target Language", LANGUAGES, index=1, key="tgt_lang")
+
+        if convert_btn:
+            if not src_code.strip():
+                st.warning("Paste some source code first.")
+            elif src_lang == tgt_lang:
+                st.info("Source and target languages are the same.")
+            else:
+                with st.spinner(f"Converting {src_lang} → {tgt_lang}…"):
+                    result = convert_code(src_code, src_lang, tgt_lang, style_notes)
+                st.session_state["converted"]  = result
+                st.session_state["conv_langs"] = (src_lang, tgt_lang)
+
+        converted = st.session_state.get("converted", "")
+        langs     = st.session_state.get("conv_langs", ("", ""))
+
+        if converted:
+            st.success(f"✅ Converted {langs[0]} → {langs[1]}")
+
+        st.text_area("", value=converted, height=380,
+                     placeholder="# Converted code appears here…",
+                     key="tgt_code")
+
+# ════════════════════════
+# TAB 2 — EXPLAIN
+# ════════════════════════
+with tab2:
+    col_l, col_r = st.columns(2, gap="medium")
+
+    with col_l:
+        st.markdown("### Paste Code to Explain")
+        exp_lang = st.selectbox("Language", LANGUAGES, key="exp_lang")
+        exp_code = st.text_area("", height=380, placeholder="# Paste code here…", key="exp_code")
+        exp_btn  = st.button("💡 Explain", type="primary", use_container_width=True)
+
+    with col_r:
+        st.markdown("### AI Explanation")
+        if exp_btn:
+            if not exp_code.strip():
+                st.warning("Paste some code first.")
+            else:
+                with st.spinner("Explaining…"):
+                    st.session_state["explanation"] = explain_code(exp_code, exp_lang)
+
+        if st.session_state.get("explanation"):
+            st.markdown(st.session_state["explanation"])
+        else:
+            st.caption("Explanation will appear here after you click Explain.")
+
+# ════════════════════════
+# TAB 3 — DETECT
+# ════════════════════════
+with tab3:
+    col_l, col_r = st.columns(2, gap="medium")
+
+    with col_l:
+        st.markdown("### Mystery Code")
+        det_code = st.text_area("", height=380, placeholder="# Paste any code here…", key="det_code")
+        det_btn  = st.button("🔎 Detect Language", type="primary", use_container_width=True)
+
+    with col_r:
+        st.markdown("### Detection Result")
+        if det_btn:
+            if not det_code.strip():
+                st.warning("Paste some code first.")
+            else:
+                with st.spinner("Analysing…"):
+                    detected, conf, reason, _ = validate_language(det_code, "")
+                st.metric("Detected Language", detected)
+                st.metric("Confidence", conf.capitalize())
+                st.info(reason)
+        else:
+            st.caption("Results will appear here after detection.")
+
+st.markdown("---")
+st.markdown("<center style='color:#4a5068;font-size:0.78rem'>CodeShift · GPT-4o · Built with Streamlit</center>", unsafe_allow_html=True)