"""
app.py — Gradio Blocks UI for Research Draft.

Provides a clean, academic interface with two roles:
  • Student    — upload PDF, generate abstract, view result.
  • Researcher — same as Student + view history, export results.

Launch:
    python app.py
"""

import gradio as gr

from abstract_service import generate_abstract_from_pdf
from history_manager import (
    get_history_as_table,
    clear_history,
    export_latest_to_txt,
    export_full_history_to_txt,
)

# ---------------------------------------------------------------------------
# CSS — minimal overrides for a clean academic look
# ---------------------------------------------------------------------------

CUSTOM_CSS = """
.main-title {
    text-align: center;
    margin-bottom: 0.2em;
}
.sub-title {
    text-align: center;
    color: #555;
    font-size: 0.95em;
    margin-top: 0;
}
"""

# ---------------------------------------------------------------------------
# Event handlers
# ---------------------------------------------------------------------------

def on_role_change(role: str):
    """Toggle visibility of the Researcher-only section."""
    return gr.Column(visible=(role == "Researcher"))


def on_generate(pdf_file, role: str):
    """
    Handle the Generate Abstract button click.

    Returns: (abstract_text, status_message)
    """
    if pdf_file is None:
        raise gr.Error("Please upload a PDF file first.")

    # Gradio file path — handle both v5 (.name) and v6 (.path)
    file_path = getattr(pdf_file, "path", None) or getattr(pdf_file, "name", None)
    if not file_path:
        raise gr.Error("Could not read the uploaded file path.")

    try:
        result = generate_abstract_from_pdf(file_path=file_path, role=role)
    except ValueError as exc:
        raise gr.Error(str(exc))
    except RuntimeError as exc:
        raise gr.Error(str(exc))
    except FileNotFoundError as exc:
        raise gr.Error(str(exc))
    except Exception as exc:
        raise gr.Error(f"Unexpected error: {exc}")

    return result["abstract"], f"✅ {result['status']}"


def on_view_history():
    """Load history rows for the Dataframe."""
    rows = get_history_as_table()
    if not rows:
        gr.Info("No history entries yet.")
    return rows


def on_clear_history():
    """Wipe the persistent history file and return an empty table."""
    clear_history()
    gr.Info("History cleared.")
    return []


def on_export_latest():
    """Export the latest abstract to a .txt download."""
    path = export_latest_to_txt()
    if path is None:
        raise gr.Error("Nothing to export — history is empty.")
    return path


def on_export_full():
    """Export the entire history to a .txt download."""
    path = export_full_history_to_txt()
    if path is None:
        raise gr.Error("Nothing to export — history is empty.")
    return path


# ---------------------------------------------------------------------------
# UI layout (Gradio Blocks)
# ---------------------------------------------------------------------------

with gr.Blocks(title="Research Draft") as demo:

    # ── Header ────────────────────────────────────────────────────────────
    gr.Markdown(
        "<h1 class='main-title'>📄 Research Draft</h1>",
    )
    gr.Markdown(
        "<p class='sub-title'>"
        "AI-powered academic abstract generation · Local &amp; Private"
        "</p>",
    )

    # ── Role selector ─────────────────────────────────────────────────────
    with gr.Row():
        role_dropdown = gr.Dropdown(
            choices=["Student", "Researcher"],
            value="Student",
            label="Select your role",
            scale=1,
            interactive=True,
        )

    gr.Markdown("---")

    # ── Main generation section (visible to all roles) ────────────────────
    gr.Markdown("### Upload & Generate")
    with gr.Row():
        with gr.Column(scale=2):
            pdf_input = gr.File(
                label="Upload Research Paper (PDF)",
                file_types=[".pdf"],
                file_count="single",
            )
            generate_btn = gr.Button(
                "🔍 Generate Abstract",
                variant="primary",
                size="lg",
            )
            status_box = gr.Textbox(
                label="Status",
                interactive=False,
                lines=1,
                placeholder="Upload a PDF and click Generate…",
            )

        with gr.Column(scale=3):
            abstract_output = gr.Textbox(
                label="Generated Abstract",
                interactive=False,
                lines=12,
                buttons=["copy"],
                placeholder="Your generated abstract will appear here…",
            )

    # ── Researcher-only section ───────────────────────────────────────────
    with gr.Column(visible=False) as researcher_section:
        gr.Markdown("---")
        gr.Markdown("### 🔬 Researcher Tools")

        with gr.Row():
            view_history_btn = gr.Button("📋 View History")
            clear_history_btn = gr.Button("🗑️ Clear History")
            export_latest_btn = gr.Button("📥 Export Latest")
            export_full_btn = gr.Button("📥 Export Full History")

        history_table = gr.Dataframe(
            headers=["Timestamp", "Role", "Filename", "Abstract (preview)"],
            datatype=["str", "str", "str", "str"],
            interactive=False,
            wrap=True,
            label="Generation History",
        )

        export_file = gr.File(
            label="Download Export",
            interactive=False,
        )

    # ── Footer ────────────────────────────────────────────────────────────
    gr.Markdown(
        "<br><center style='color:#999; font-size:0.8em;'>"
        "Research Draft · B.Tech Final Year Project · Runs 100 % locally"
        "</center>"
    )

    # ── Event wiring ──────────────────────────────────────────────────────

    # Role switch → show/hide researcher section
    role_dropdown.change(
        fn=on_role_change,
        inputs=role_dropdown,
        outputs=researcher_section,
    )

    # Generate abstract
    generate_btn.click(
        fn=on_generate,
        inputs=[pdf_input, role_dropdown],
        outputs=[abstract_output, status_box],
    )

    # Researcher tools
    view_history_btn.click(
        fn=on_view_history,
        outputs=history_table,
    )
    clear_history_btn.click(
        fn=on_clear_history,
        outputs=history_table,
    )
    export_latest_btn.click(
        fn=on_export_latest,
        outputs=export_file,
    )
    export_full_btn.click(
        fn=on_export_full,
        outputs=export_file,
    )


# ---------------------------------------------------------------------------
# Entry point
# ---------------------------------------------------------------------------

if __name__ == "__main__":
    demo.launch(
        server_name="0.0.0.0",
        server_port=7860,
        show_error=True,
        css=CUSTOM_CSS,
    )