import gradio as gr
import pandas as pd
import os
from datetime import datetime, timedelta


# ---------------- CONFIG ---------------- #

STAFF_FILE = "staff_details.xlsx"
PERMISSION_FILE = "permissions.xlsx"

ADMIN_USER = "admin"
ADMIN_PASS = "admin123"


# ---------------- INIT ---------------- #

if not os.path.exists(PERMISSION_FILE):
    df = pd.DataFrame(columns=[
        "StaffID",
        "Name",
        "Department",
        "Date",
        "FromTime",
        "ToTime",
        "Reason",
        "SubmittedOn"
    ])
    df.to_excel(PERMISSION_FILE, index=False)


# ---------------- LOADERS ---------------- #

def load_staff():
    return pd.read_excel(STAFF_FILE)


def load_permissions():
    return pd.read_excel(PERMISSION_FILE)


# ---------------- VALIDATORS ---------------- #

# Date: Only Today / Tomorrow / Day after Tomorrow
def validate_date_range(date_str):

    try:
        d = datetime.strptime(date_str, "%d/%m/%Y").date()
    except:
        return False, "❌ Date format must be DD/MM/YYYY"

    today = datetime.today().date()
    max_day = today + timedelta(days=2)

    if d < today:
        return False, "❌ Past date not allowed"

    if d > max_day:
        return False, "❌ Apply only within 2 days"

    return True, ""


# Time: 08:45 - 17:20 and exactly 1 hour
def validate_time_range(f, t):

    try:
        f_time = datetime.strptime(f, "%H:%M")
        t_time = datetime.strptime(t, "%H:%M")
    except:
        return False, "❌ Time format must be HH:MM (24-hour)"

    min_time = datetime.strptime("08:45", "%H:%M")
    max_time = datetime.strptime("17:20", "%H:%M")

    # Check range
    if f_time < min_time or t_time > max_time:
        return False, "❌ Time allowed: 08:45 to 17:20 only"

    # Check 1 hour duration
    diff = (t_time - f_time).total_seconds() / 3600

    if diff != 1:
        return False, "❌ Permission must be exactly 1 hour"

    return True, ""


# ---------------- STAFF FUNCTIONS ---------------- #

def fetch_staff(staff_id):

    df = load_staff()
    row = df[df["StaffID"] == staff_id]

    if row.empty:
        return "Not Found", "Not Found", "0"

    name = row.iloc[0]["Name"]
    dept = row.iloc[0]["Department"]

    perms = load_permissions()
    count = len(perms[perms["StaffID"] == staff_id])

    return name, dept, str(count)


def submit_permission(staff_id, date, f, t, reason):

    # Basic validation
    if staff_id.strip() == "":
        return "❌ Staff ID Required"

    if date.strip() == "":
        return "❌ Date Required"

    if f.strip() == "" or t.strip() == "":
        return "❌ Time Required"

    if reason.strip() == "":
        return "❌ Reason Required"


    # Date validation
    ok, msg = validate_date_range(date)
    if not ok:
        return msg


    # Time validation
    ok, msg = validate_time_range(f, t)
    if not ok:
        return msg


    # Staff validation
    staff = load_staff()
    row = staff[staff["StaffID"] == staff_id]

    if row.empty:
        return "❌ Invalid Staff ID"


    perms = load_permissions()


    # Same day check (max 2)
    same_day = perms[
        (perms["StaffID"] == staff_id) &
        (perms["Date"] == date)
    ]

    if len(same_day) == 1:
        return "⚠️ Second permission today → Apply Leave"

    if len(same_day) >= 2:
        return "❌ Daily limit reached"


    # Monthly limit (2 only)
    m = date.split("/")[1]
    y = date.split("/")[2]

    same_month = perms[
        (perms["StaffID"] == staff_id) &
        (perms["Date"].str.contains(f"/{m}/{y}", na=False))
    ]

    if len(same_month) >= 2:
        return "❌ Monthly limit reached (2 only)"


    # Save
    name = row.iloc[0]["Name"]
    dept = row.iloc[0]["Department"]

    now = datetime.now().strftime("%d/%m/%Y %H:%M")

    new_row = {
        "StaffID": staff_id,
        "Name": name,
        "Department": dept,
        "Date": date,
        "FromTime": f,
        "ToTime": t,
        "Reason": reason,
        "SubmittedOn": now
    }

    perms = pd.concat([perms, pd.DataFrame([new_row])], ignore_index=True)
    perms.to_excel(PERMISSION_FILE, index=False)

    return "✅ Permission Submitted Successfully"


def delete_permission(staff_id, date):

    perms = load_permissions()
    before = len(perms)

    perms = perms[
        ~((perms["StaffID"] == staff_id) &
          (perms["Date"] == date))
    ]

    perms.to_excel(PERMISSION_FILE, index=False)

    if len(perms) == before:
        return "❌ No Record Found"
    else:
        return "✅ Deleted"


def clear_form():
    return "", "", "", "", ""


# ---------------- ADMIN ---------------- #

def admin_login(user, pwd):

    if user == ADMIN_USER and pwd == ADMIN_PASS:
        return gr.update(visible=True), "✅ Login Successful"

    return gr.update(visible=False), "❌ Invalid Login"


def get_all_data():
    return load_permissions()


def download_excel():
    return PERMISSION_FILE


def monthly_report(month, year):

    perms = load_permissions()

    return perms[
        perms["Date"].str.contains(f"/{month}/{year}", na=False)
    ]


def dept_report(dept):

    perms = load_permissions()

    return perms[perms["Department"] == dept]


def reset_data():

    df = pd.DataFrame(columns=[
        "StaffID",
        "Name",
        "Department",
        "Date",
        "FromTime",
        "ToTime",
        "Reason",
        "SubmittedOn"
    ])

    df.to_excel(PERMISSION_FILE, index=False)

    return "✅ All Data Cleared"


# ================= UI ================= #

with gr.Blocks() as app:

    gr.HTML("""
    <center>
        <h2>SRC, SASTRA</h2>
        <h3>Staff Permission Management System</h3>
        <hr>
    </center>
    """)


    # ---------------- STAFF TAB ---------------- #

    with gr.Tab("Staff Panel"):

        with gr.Row():

            with gr.Column():

                staff_id = gr.Textbox(label="Staff ID")

                name = gr.Textbox(label="Name", interactive=False)
                dept = gr.Textbox(label="Department", interactive=False)
                count = gr.Textbox(label="Permission Count", interactive=False)

                fetch = gr.Button("Fetch Details")


            with gr.Column():

                date = gr.Textbox(label="Date (DD/MM/YYYY)")
                f = gr.Textbox(label="From (HH:MM 24-hr)")
                t = gr.Textbox(label="To (HH:MM 24-hr)")

                reason = gr.Textbox(label="Reason", lines=3)

                with gr.Row():
                    submit = gr.Button("Submit", variant="primary")
                    delete = gr.Button("Delete", variant="stop")
                    clear = gr.Button("Clear")

                status = gr.Textbox(label="Status", interactive=False)


    # ---------------- ADMIN TAB ---------------- #

    with gr.Tab("Admin Panel"):

        admin_user = gr.Textbox(label="Username")
        admin_pwd = gr.Textbox(label="Password", type="password")

        login = gr.Button("Login")

        msg = gr.Textbox(interactive=False)

        admin_box = gr.Column(visible=False)

        with admin_box:

            gr.Markdown("### 📊 All Records")

            table = gr.Dataframe(interactive=False)

            refresh = gr.Button("Refresh")


            gr.Markdown("### 📅 Monthly Report")

            month = gr.Textbox(label="Month (MM)")
            year = gr.Textbox(label="Year (YYYY)")

            month_btn = gr.Button("Generate")

            month_table = gr.Dataframe()


            gr.Markdown("### 🏢 Department Report")

            dept_name = gr.Textbox(label="Department")

            dept_btn = gr.Button("Generate")

            dept_table = gr.Dataframe()


            gr.Markdown("### 📥 Download")

            down = gr.Button("Download Excel")

            file = gr.File()


            gr.Markdown("### ⚠️ Reset")

            reset = gr.Button("Reset All", variant="stop")

            reset_msg = gr.Textbox(interactive=False)


    # ---------------- EVENTS ---------------- #

    fetch.click(fetch_staff, staff_id, [name, dept, count])

    submit.click(
        submit_permission,
        [staff_id, date, f, t, reason],
        status
    )

    delete.click(delete_permission, [staff_id, date], status)

    clear.click(clear_form, outputs=[date, f, t, reason, status])


    login.click(admin_login, [admin_user, admin_pwd], [admin_box, msg])

    refresh.click(get_all_data, outputs=table)

    month_btn.click(monthly_report, [month, year], month_table)

    dept_btn.click(dept_report, dept_name, dept_table)

    down.click(download_excel, outputs=file)

    reset.click(reset_data, outputs=reset_msg)


app.launch()