#!/usr/bin/env python3
"""
WebUntis Absence Viewer
-----------------------
Fetches your absences from WebUntis, displays them in an interactive
prompt_toolkit TUI (newest first, filterable), and can fill & export
the school's Entschuldigung PDF template.

Requirements:
    pip install requests prompt_toolkit pypdf

Usage:
    python webuntis_absences.py
    python webuntis_absences.py --server mese.webuntis.com --school MySchool
    python webuntis_absences.py --template /path/to/Entschuldigung_template.pdf
"""

import argparse
import getpass
import json
import os
import sys
from datetime import date, datetime, timedelta
from pathlib import Path

import requests
from prompt_toolkit import Application
from prompt_toolkit.formatted_text import HTML
from prompt_toolkit.key_binding import KeyBindings
from prompt_toolkit.layout import HSplit, Layout
from prompt_toolkit.layout.containers import Window
from prompt_toolkit.layout.controls import FormattedTextControl
from prompt_toolkit.styles import Style
from prompt_toolkit.widgets import Frame, TextArea

# ─── WebUntis API ─────────────────────────────────────────────────────────────

class WebUntisClient:
    """Minimal WebUntis client using JSON-RPC + REST endpoints."""

    def __init__(self, server: str, school: str):
        self.base_url    = f"https://{server}/WebUntis"
        self.school      = school
        self.session     = requests.Session()
        self.session.headers.update({
            "Content-Type":    "application/json",
            "User-Agent":      "WebUntisAbsenceViewer/1.0",
            "X-Requested-With": "XMLHttpRequest",
        })
        self._rpc_id     = 0
        self.person_id:   int | None = None
        self.person_type: int | None = None
        self.display_name: str = ""     # real name from getUserData2017

    def _rpc(self, method: str, params: dict | None = None) -> dict:
        self._rpc_id += 1
        payload = {
            "jsonrpc": "2.0",
            "method":  method,
            "params":  params or {},
            "id":      str(self._rpc_id),
        }
        resp = self.session.post(
            f"{self.base_url}/jsonrpc.do?school={self.school}",
            json=payload,
            timeout=15,
        )
        resp.raise_for_status()
        data = resp.json()
        if "error" in data:
            raise RuntimeError(f"WebUntis RPC error: {data['error']}")
        return data.get("result", {})

    def login(self, username: str, password: str) -> None:
        result = self._rpc("authenticate", {
            "user":     username,
            "password": password,
            "client":   "WebUntisAbsenceViewer",
        })
        self.person_id   = result.get("personId")
        self.person_type = result.get("personType")
        if not self.person_id:
            raise RuntimeError("Login succeeded but no personId returned.")
        # Fetch the real display name (login name ≠ student name)
        try:
            ud = self._rpc("getUserData2017")
            self.display_name = (
                ud.get("userData", {}).get("displayName")
                or ud.get("displayName")
                or ""
            )
        except Exception:
            pass  # non-critical

    def logout(self) -> None:
        try:
            self._rpc("logout")
        except Exception:
            pass

    def get_absences(self, start: date, end: date) -> list[dict]:
        """REST endpoint first, JSON-RPC fallback."""
        url = (
            f"{self.base_url}/api/classreg/absences/students"
            f"?startDate={start.strftime('%Y%m%d')}"
            f"&endDate={end.strftime('%Y%m%d')}"
            f"&studentId={self.person_id}"
            f"&excuseStatusId=-1"
        )
        resp = self.session.get(url, timeout=15)
        if resp.status_code == 200:
            data = resp.json()
            absences = (
                data.get("data", {}).get("absences")
                or data.get("absences")
                or data.get("data")
                or []
            )
            if isinstance(absences, list):
                return absences

        # Fallback
        result = self._rpc("getTimetableWithAbsences", {
            "options": {
                "startDate": int(start.strftime("%Y%m%d")),
                "endDate":   int(end.strftime("%Y%m%d")),
                "element": {
                    "id":   self.person_id,
                    "type": self.person_type or 5,
                },
            }
        })
        absences = []
        for period in result if isinstance(result, list) else result.get("periods", []):
            for ab in period.get("absences", []):
                ab["date"]      = period.get("date", "")
                ab["startTime"] = period.get("startTime", "")
                ab["endTime"]   = period.get("endTime", "")
                absences.append(ab)
        return absences

    def get_student_class(self) -> str:
        """Try to get the student's current class/Klasse."""
        try:
            ud = self._rpc("getUserData2017")
            # look for class in userData
            klassen = (
                ud.get("userData", {}).get("klassenName")
                or ud.get("userData", {}).get("klasse")
                or ""
            )
            return klassen
        except Exception:
            return ""


# ─── Sorting & filtering ───────────────────────────────────────────────────────

def _absence_sort_key(ab: dict):
    """Return a comparable key for sorting (newest first)."""
    date_val = ab.get("date") or ab.get("startDate") or 0
    time_val = ab.get("startTime") or ab.get("lessonStartTime") or 0
    try:
        return (int(date_val), int(time_val))
    except (ValueError, TypeError):
        return (0, 0)


def _is_unexcused(ab: dict) -> bool:
    excused = ab.get("isExcused") or ab.get("excused") or ab.get("excuse")
    print(f"Debug: Absence {ab.get('id', '?')} excuse status: {excused}")
    return excused


def filter_absences(absences: list[dict], unexcused_only: bool) -> list[dict]:
    if unexcused_only:
        absences = [a for a in absences if _is_unexcused(a)]
    return sorted(absences, key=_absence_sort_key, reverse=True)


# ─── Formatting ────────────────────────────────────────────────────────────────

def _parse_dt(date_int, time_int) -> str:
    try:
        d = str(date_int)
        t = str(time_int).zfill(4)
        dt = datetime(int(d[:4]), int(d[4:6]), int(d[6:8]),
                      int(t[:2]), int(t[2:]))
        return dt.strftime("%d.%m.%Y %H:%M")
    except Exception:
        return f"{date_int} {time_int}"


def _excuse_label(ab: dict) -> str:
    excused = ab.get("isExcused") or ab.get("excused") or ab.get("excuse")
    if excused is True or excused == 1:
        return "✓ Excused"
    # if excused is False or excused == 0:
    else:
        return "✗ Unexcused"
    return "? Unknown"


def format_absence(ab: dict, idx: int) -> str:
    date_val = ab.get("date") or ab.get("startDate", "")
    start    = ab.get("startTime") or ab.get("lessonStartTime", "")
    end      = ab.get("endTime")   or ab.get("lessonEndTime", "")
    subject  = ab.get("subject") or ab.get("subjectLong") or ab.get("subjectName") or "—"
    teacher  = ab.get("teacher")  or ab.get("teacherName") or "—"
    reason   = ab.get("reason")   or ab.get("text") or ""
    excuse   = _excuse_label(ab)
    minutes  = ab.get("absentTime") or ab.get("minutesAbsent") or ""

    if date_val and start:
        when     = _parse_dt(date_val, start)
        when_end = _parse_dt(date_val, end) if end else ""
        time_str = when + (f" → {when_end.split(' ')[1]}" if when_end else "")
    else:
        time_str = str(date_val) or "unknown"

    lines = [
        f"  #{idx+1:<3}  {time_str}",
        f"       Subject : {subject}",
        f"       Teacher : {teacher}",
        f"       Status  : {excuse}",
    ]
    if minutes:
        lines.append(f"       Minutes : {minutes}")
    if reason:
        lines.append(f"       Reason  : {reason}")
    lines.append("")
    return "\n".join(lines)


def build_display(absences: list[dict], title: str) -> str:
    if not absences:
        return "  No absences found for the selected period / filter.\n"
    header = f"  {title}\n  {'─' * 60}\n\n"
    body   = "".join(format_absence(ab, i) for i, ab in enumerate(absences))
    footer = f"\n  Total: {len(absences)} absence(s)\n"
    return header + body + footer


# ─── PDF filling ───────────────────────────────────────────────────────────────

def fill_entschuldigung(
    template_path: str,
    output_dir: str,
    student_name: str,
    student_class: str,
    absence_dates: str,          # e.g. "12.06.2025 – 13.06.2025"
    reason: str,
    total_hours: int,
    workshop_hours: int,
    sign_date: str,              # e.g. "16.06.2025"
) -> str:
    """Fill the Entschuldigung PDF form and return the output path."""
    try:
        from pypdf import PdfReader, PdfWriter
    except ImportError:
        raise RuntimeError("pypdf is required: pip install pypdf")

    reader = PdfReader(template_path)
    writer = PdfWriter()
    writer.append(reader)

    # Field mapping (confirmed from extract_form_field_info):
    # Textfeld 1 → Name des Schülers
    # Textfeld 2 → Klasse
    # Textfeld 4 → Versäumte(r) Unterrichtstag(e) / Datum
    # Textfeld 3 → Begründung für das Fernbleiben
    # Textfeld 5 → Zahl der versäumten Unterrichtsstunden
    # Textfeld 6 → davon versäumte Werkstättenstunden
    # Textfeld 7 → Datum (signature date, bottom left)

    fields = {
        "Textfeld 1": student_name,
        "Textfeld 2": student_class,
        "Textfeld 4": absence_dates,
        "Textfeld 3": reason,
        "Textfeld 5": str(total_hours),
        "Textfeld 6": str(workshop_hours),
        "Textfeld 7": sign_date,
    }

    writer.update_page_form_field_values(writer.pages[0], fields)

    # Derive date for filename from absence_dates (take first date portion)
    try:
        first_date = absence_dates.split("–")[0].strip().split(" ")[0]
        dt = datetime.strptime(first_date, "%d.%m.%Y")
        date_suffix = dt.strftime("%d%m%Y")
    except Exception:
        date_suffix = datetime.now().strftime("%d%m%Y")

    output_filename = f"Entschuldigung{date_suffix}.pdf"
    output_path     = os.path.join(output_dir, output_filename)

    with open(output_path, "wb") as f:
        writer.write(f)

    return output_path


# ─── PDF export dialog ─────────────────────────────────────────────────────────

def run_pdf_export_dialog(
    absences: list[dict],
    template_path: str,
    student_name: str,
    student_class: str,
) -> None:
    """Simple terminal prompts to collect data and fill the PDF."""
    print("\n─── Export Entschuldigung PDF ─────────────────────────────")

    # Pick absence(s) to excuse
    unexcused = [a for a in absences if _is_unexcused(a)]
    if not unexcused:
        print("No unexcused absences found.")
        return

    print("\nUnexcused absences:")
    for i, ab in enumerate(unexcused[:20]):
        date_val = ab.get("date") or ab.get("startDate", "")
        start    = ab.get("startTime") or ab.get("lessonStartTime", "")
        print(f"  [{i+1}] {_parse_dt(date_val, start)}")

    sel = input("\nEnter number(s) to excuse (comma-separated, or 'all'): ").strip()
    if sel.lower() == "all":
        selected = unexcused[:20]
    else:
        indices = [int(x.strip()) - 1 for x in sel.split(",") if x.strip().isdigit()]
        selected = [unexcused[i] for i in indices if 0 <= i < len(unexcused)]

    if not selected:
        print("No valid selection.")
        return

    # Build date string
    dates_sorted = sorted(selected, key=_absence_sort_key)
    date_strs = []
    for ab in dates_sorted:
        dv = ab.get("date") or ab.get("startDate", "")
        try:
            d = str(dv)
            date_strs.append(f"{d[6:8]}.{d[4:6]}.{d[:4]}")
        except Exception:
            date_strs.append(str(dv))
    unique_dates = list(dict.fromkeys(date_strs))
    absence_dates = ", ".join(unique_dates)

    # Count hours (each absence period ≈ 1 lesson; use absentTime if available)
    total_minutes = sum(
        int(ab.get("absentTime") or ab.get("minutesAbsent") or 50)
        for ab in selected
    )
    total_hours = max(1, round(total_minutes / 50))

    # Prompt user for details
    print(f"\n  Student name : {student_name or '(unknown)'}")
    name_input = input(f"  Override name? [Enter to keep]: ").strip()
    final_name  = name_input if name_input else student_name

    print(f"  Class        : {student_class or '(unknown)'}")
    class_input = input(f"  Override class? [Enter to keep]: ").strip()
    final_class  = class_input if class_input else student_class

    print(f"  Absence date(s): {absence_dates}")
    date_override = input(f"  Override date(s)? [Enter to keep]: ").strip()
    final_dates   = date_override if date_override else absence_dates

    default_reason = (selected[0].get("reason") or selected[0].get("text") or "Krankheit")
    reason_input  = input(f"  Reason [{default_reason}]: ").strip()
    final_reason  = reason_input if reason_input else default_reason

    print(f"  Total lessons missed: {total_hours}")
    hours_input = input(f"  Override? [Enter to keep]: ").strip()
    final_hours = int(hours_input) if hours_input.isdigit() else total_hours

    workshop_input = input(f"  Workshop hours missed [0]: ").strip()
    final_workshop = int(workshop_input) if workshop_input.isdigit() else 0

    sign_date = input(
        f"  Signature date [{datetime.now().strftime('%d.%m.%Y')}]: "
    ).strip() or datetime.now().strftime("%d.%m.%Y")

    output_dir = input(
        f"  Save to directory [{os.getcwd()}]: "
    ).strip() or os.getcwd()

    try:
        out = fill_entschuldigung(
            template_path=template_path,
            output_dir=output_dir,
            student_name=final_name,
            student_class=final_class,
            absence_dates=final_dates,
            reason=final_reason,
            total_hours=final_hours,
            workshop_hours=final_workshop,
            sign_date=sign_date,
        )
        print(f"\n✅  Saved: {out}\n")
    except Exception as e:
        print(f"\n❌  Failed to fill PDF: {e}\n")


# ─── TUI ──────────────────────────────────────────────────────────────────────

STYLE = Style.from_dict({
    "frame.border": "ansicyan",
    "frame.title":  "bold ansicyan",
    "status":       "reverse ansicyan",
    "text-area":    "ansiwhite",
})


def run_tui(
    all_absences: list[dict],
    server: str,
    school: str,
    start: date,
    end: date,
    template_path: str | None,
    student_name: str,
    student_class: str,
) -> None:
    state = {
        "filter": False,   # True = show only unexcused
    }

    def _render() -> str:
        filtered = filter_absences(all_absences, state["filter"])
        mode     = "Unexcused only" if state["filter"] else "All absences"
        title    = (
            f"{school} | {start.strftime('%d.%m.%Y')} – {end.strftime('%d.%m.%Y')} | {mode}"
        )
        return build_display(filtered, title)

    content = TextArea(
        text=_render(),
        read_only=True,
        scrollbar=True,
        style="class:text-area",
        wrap_lines=False,
    )

    def _refresh():
        content.text = _render()

    kb = KeyBindings()

    @kb.add("q")
    @kb.add("c-c")
    @kb.add("c-q")
    def _quit(event):
        event.app.exit()

    @kb.add("f")
    def _toggle_filter(event):
        state["filter"] = not state["filter"]
        _refresh()

    @kb.add("e")
    def _export(event):
        if template_path:
            event.app.exit(result="export")
        # if no template, key does nothing

    pdf_hint = "  <b>[E]</b> Export PDF" if template_path else ""
    status_bar = Window(
        content=FormattedTextControl(
            HTML(
                " <b>[Q]</b> Quit"
                "  <b>[F]</b> Toggle unexcused filter"
                f"{pdf_hint}"
                "  <b>[↑/↓]</b> Scroll"
                f"  <b>Fetched:</b> {datetime.now().strftime('%H:%M:%S')}"
            )
        ),
        height=1,
        style="class:status",
    )

    root = HSplit([
        Frame(
            body=content,
            title=" 📅 WebUntis Absence Viewer ",
            style="class:frame",
        ),
        status_bar,
    ])

    app = Application(
        layout=Layout(root),
        key_bindings=kb,
        style=STYLE,
        full_screen=True,
        mouse_support=True,
    )
    result = app.run()

    if result == "export" and template_path:
        run_pdf_export_dialog(
            absences=all_absences,
            template_path=template_path,
            student_name=student_name,
            student_class=student_class,
        )


# ─── CLI ──────────────────────────────────────────────────────────────────────

def prompt_missing(args):
    if not args.server:
        args.server   = input("WebUntis server (e.g. mese.webuntis.com): ").strip()
    if not args.school:
        args.school   = input("School name (from the WebUntis URL): ").strip()
    if not args.username:
        args.username = input("Username: ").strip()
    if not args.password:
        args.password = getpass.getpass("Password: ")


def main():
    parser = argparse.ArgumentParser(description="WebUntis Absence Viewer")
    parser.add_argument("--server",   help="WebUntis hostname, e.g. mese.webuntis.com")
    parser.add_argument("--school",   help="School name (from the WebUntis URL)")
    parser.add_argument("--username", help="Your WebUntis username")
    parser.add_argument("--password", help="Your WebUntis password (omit to be prompted)")
    parser.add_argument("--days",     type=int, default=365,
                        help="How many past days to include (default: 365)")
    parser.add_argument("--template", help="Path to Entschuldigung PDF template",
                        default=None)
    args = parser.parse_args()

    prompt_missing(args)

    end_date   = date.today()
    start_date = end_date - timedelta(days=args.days)

    print(f"Connecting to {args.server} …")
    client = WebUntisClient(server=args.server, school=args.school)

    try:
        print("Logging in …")
        client.login(args.username, args.password)

        student_name  = client.display_name
        student_class = client.get_student_class()

        print(f"Logged in as: {args.username}"
              + (f" (name: {student_name})" if student_name else ""))
        print(f"Fetching absences from {start_date} to {end_date} …")
        absences = client.get_absences(start_date, end_date)
        print(f"Got {len(absences)} absence(s). Launching viewer …")
    except Exception as exc:
        print(f"\n❌  Error: {exc}", file=sys.stderr)
        sys.exit(1)
    finally:
        client.logout()

    run_tui(
        all_absences=absences,
        server=args.server,
        school=args.school,
        start=start_date,
        end=end_date,
        template_path=args.template,
        student_name=student_name,
        student_class=student_class,
    )


if __name__ == "__main__":
    main()