#!/usr/bin/env python3
"""Generate a KBR4 invoice PDF for Audact AI Ltd."""

from __future__ import annotations

import os
import sys
from dataclasses import dataclass
from datetime import date, datetime, timedelta
from pathlib import Path

from reportlab.lib.colors import HexColor, black, white
from reportlab.lib.pagesizes import A4
from reportlab.lib.utils import ImageReader
from reportlab.pdfgen import canvas


SUPPLIER = {
    "name": "Kompanija Broj 4 D.O.O.",
    "address_lines": ["Hakije Turajlica 2", "71000 Sarajevo", "Bosnia and Herzegovina"],
    "tax_id": "4202962240000",
    "vat_id": "202962240000",
}

CUSTOMER = {
    "name": "Audact AI Ltd",
    "address_lines": [
        "71-75 Shelton Street",
        "Covent Garden",
        "London WC2H 9JQ",
        "United Kingdom",
    ],
    "company_no": "17059133",
}

PAYMENT = {
    "iban": "BA391610000270960005",
    "swift": "RZBABA2S",
    "beneficiary_name": "KOMPANIJA BROJ 4 DOO SARAJEVO",
    "beneficiary_address": [
        "HAKIJE TURAJLICA BROJ 2",
        "71000 Sarajevo",
        "Bosnia and Herzegovina",
    ],
    "bank_name": "RAIFFEISEN BANK DD BOSNA I HERCEGOVINA",
    "bank_address": [
        "ZMAJA OD BOSNE BB",
        "71000 SARAJEVO",
        "Bosnia and Herzegovina",
    ],
}

LINE_ITEM_DESCRIPTION_LINES = [
    "Technical leadership and development services",
    "for the Audact platform",
]

ASSETS_DIR = Path(__file__).resolve().parent / "assets"
LOGO_PATH = ASSETS_DIR / "logo.png"

DARK = HexColor("#3F3F3F")
GRAY = HexColor("#7A7A7A")
LIGHT_GRAY = HexColor("#EAEAEA")
TABLE_HEAD = HexColor("#4A4A4A")


@dataclass
class InvoiceInputs:
    number: str
    period_start: date
    period_end: date
    total_amount: float

    @property
    def issue_date(self) -> date:
        return date.today()

    @property
    def due_date(self) -> date:
        return self.issue_date + timedelta(days=5)


def prompt_str(label: str, validator=None) -> str:
    while True:
        value = input(f"{label}: ").strip()
        if not value:
            print("  Value required.")
            continue
        if validator:
            err = validator(value)
            if err:
                print(f"  {err}")
                continue
        return value


def parse_date(s: str) -> date:
    for fmt in ("%Y-%m-%d", "%d.%m.%Y", "%d/%m/%Y"):
        try:
            return datetime.strptime(s, fmt).date()
        except ValueError:
            continue
    raise ValueError("expected YYYY-MM-DD, DD.MM.YYYY, or DD/MM/YYYY")


def prompt_date(label: str) -> date:
    while True:
        raw = input(f"{label}: ").strip()
        try:
            return parse_date(raw)
        except ValueError as e:
            print(f"  {e}")


def prompt_amount(label: str) -> float:
    while True:
        raw = input(f"{label}: ").strip().replace(",", ".").replace("€", "").replace(" ", "")
        try:
            value = float(raw)
            if value <= 0:
                raise ValueError
            return value
        except ValueError:
            print("  Enter a positive number, e.g. 7250 or 7250.00")


def gather_inputs() -> InvoiceInputs:
    print("KBR4 invoice generator — Audact AI Ltd")
    print("-" * 40)
    number = prompt_str("Invoice number (e.g. 1/2026)")
    print("Invoice period (two-week range, in arrears):")
    start = prompt_date("  Period start (YYYY-MM-DD)")
    while True:
        end = prompt_date("  Period end   (YYYY-MM-DD)")
        if end < start:
            print("  End must be on or after start.")
            continue
        break
    total = prompt_amount("Total amount in EUR")
    return InvoiceInputs(number=number, period_start=start, period_end=end, total_amount=total)


def fmt_money(amount: float) -> str:
    return f"€{amount:,.2f}"


def fmt_date_long(d: date) -> str:
    return d.strftime("%b ") + str(d.day) + d.strftime(", %Y")


def fmt_date_dotted(d: date) -> str:
    return f"{d.day}.{d.month}.{d.year}."


def safe_filename(invoice_number: str) -> str:
    cleaned = invoice_number.replace("/", "_").replace("\\", "_").replace(" ", "_")
    return f"Invoice_{cleaned}.pdf"


def render_pdf(inv: InvoiceInputs, output_path: Path) -> None:
    page_w, page_h = A4
    c = canvas.Canvas(str(output_path), pagesize=A4)
    c.setTitle(f"Invoice {inv.number}")
    c.setAuthor(SUPPLIER["name"])

    margin_l = 50
    margin_r = page_w - 50

    y_top = page_h - 60

    if LOGO_PATH.exists():
        logo = ImageReader(str(LOGO_PATH))
        lw, lh = logo.getSize()
        target_w = 110
        target_h = target_w * lh / lw
        c.drawImage(
            logo,
            margin_l,
            y_top - target_h + 10,
            width=target_w,
            height=target_h,
            mask="auto",
            preserveAspectRatio=True,
        )

    c.setFillColor(DARK)
    c.setFont("Helvetica", 30)
    c.drawRightString(margin_r, y_top, "INVOICE")
    c.setFont("Helvetica", 11)
    c.setFillColor(GRAY)
    c.drawRightString(margin_r, y_top - 18, f"# {inv.number}")

    y = y_top - 35
    c.setFillColor(black)
    c.setFont("Helvetica-Bold", 10.5)
    c.drawString(margin_l, y, SUPPLIER["name"])
    c.setFont("Helvetica", 9.5)
    y -= 13
    for line in SUPPLIER["address_lines"]:
        c.drawString(margin_l, y, line)
        y -= 12
    c.drawString(margin_l, y, f"TAX ID: {SUPPLIER['tax_id']}")
    y -= 12
    c.drawString(margin_l, y, f"VAT ID: {SUPPLIER['vat_id']}")
    y -= 24

    bill_top = y
    c.setFillColor(GRAY)
    c.setFont("Helvetica", 9)
    c.drawString(margin_l, bill_top, "Bill To:")
    bill_y = bill_top - 13
    c.setFillColor(black)
    c.setFont("Helvetica-Bold", 10.5)
    c.drawString(margin_l, bill_y, CUSTOMER["name"])
    c.setFont("Helvetica", 9.5)
    bill_y -= 13
    for line in CUSTOMER["address_lines"]:
        c.drawString(margin_l, bill_y, line)
        bill_y -= 12
    c.drawString(margin_l, bill_y, f"Company No: {CUSTOMER['company_no']}")
    bill_y -= 12

    meta_label_x = margin_r - 110
    meta_value_x = margin_r
    meta_y = y_top - 60

    c.setFillColor(GRAY)
    c.setFont("Helvetica", 9.5)
    c.drawRightString(meta_label_x, meta_y, "Date:")
    c.setFillColor(black)
    c.drawRightString(meta_value_x, meta_y, fmt_date_long(inv.issue_date))

    meta_y -= 18
    c.setFillColor(GRAY)
    c.drawRightString(meta_label_x, meta_y, "Due Date:")
    c.setFillColor(black)
    c.drawRightString(meta_value_x, meta_y, fmt_date_long(inv.due_date))

    meta_y -= 22
    bal_box_h = 26
    bal_box_y = meta_y - bal_box_h + 14
    c.setFillColor(LIGHT_GRAY)
    c.rect(margin_r - 230, bal_box_y, 230, bal_box_h, stroke=0, fill=1)
    c.setFillColor(black)
    c.setFont("Helvetica-Bold", 11)
    c.drawRightString(meta_label_x, meta_y, "Balance Due:")
    c.drawRightString(meta_value_x, meta_y, fmt_money(inv.total_amount))

    table_top = min(bill_y, bal_box_y) - 30
    row_h = 22

    header_y = table_top
    c.setFillColor(TABLE_HEAD)
    c.rect(margin_l, header_y - row_h + 6, margin_r - margin_l, row_h, stroke=0, fill=1)
    c.setFillColor(white)
    c.setFont("Helvetica", 10)
    item_x = margin_l + 8
    qty_right = margin_l + 320
    rate_right = margin_l + 410
    amount_right = margin_r - 8
    text_y = header_y - row_h + 12
    c.drawString(item_x, text_y, "Item")
    c.drawRightString(qty_right, text_y, "Quantity")
    c.drawRightString(rate_right, text_y, "Rate")
    c.drawRightString(amount_right, text_y, "Amount")

    weeks = 2
    rate = round(inv.total_amount / weeks, 2)
    amount = inv.total_amount

    row_y = header_y - row_h - 8
    c.setFillColor(black)
    c.setFont("Helvetica-Bold", 10)
    c.drawString(item_x, row_y, LINE_ITEM_DESCRIPTION_LINES[0])
    c.setFont("Helvetica", 10)
    c.drawRightString(qty_right, row_y, f"{weeks} weeks")
    c.drawRightString(rate_right, row_y, fmt_money(rate))
    c.drawRightString(amount_right, row_y, fmt_money(amount))
    if len(LINE_ITEM_DESCRIPTION_LINES) > 1:
        c.setFont("Helvetica-Bold", 10)
        c.setFillColor(black)
        for extra in LINE_ITEM_DESCRIPTION_LINES[1:]:
            row_y -= 13
            c.drawString(item_x, row_y, extra)

    totals_y = row_y - 50
    label_x = margin_r - 110
    value_x = margin_r
    c.setFillColor(GRAY)
    c.setFont("Helvetica", 10)
    c.drawRightString(label_x, totals_y, "Subtotal:")
    c.setFillColor(black)
    c.drawRightString(value_x, totals_y, fmt_money(amount))
    totals_y -= 16
    c.setFillColor(GRAY)
    c.drawRightString(label_x, totals_y, "Tax (0%):")
    c.setFillColor(black)
    c.drawRightString(value_x, totals_y, fmt_money(0))
    totals_y -= 16
    c.setFillColor(GRAY)
    c.drawRightString(label_x, totals_y, "Total:")
    c.setFillColor(black)
    c.setFont("Helvetica-Bold", 10.5)
    c.drawRightString(value_x, totals_y, fmt_money(amount))

    notes_y = totals_y - 50
    c.setFillColor(GRAY)
    c.setFont("Helvetica", 9)
    c.drawString(margin_l, notes_y, "Notes:")
    notes_y -= 13
    c.setFillColor(black)
    c.setFont("Helvetica", 9.5)
    c.drawString(
        margin_l,
        notes_y,
        f"Work performed from {fmt_date_dotted(inv.period_start)} - {fmt_date_dotted(inv.period_end)}",
    )
    notes_y -= 13
    c.drawString(
        margin_l,
        notes_y,
        "VAT reverse charge - Article 196 of Council Directive 2006/112/EC.",
    )

    terms_y = notes_y - 24
    c.setFillColor(GRAY)
    c.setFont("Helvetica", 9)
    c.drawString(margin_l, terms_y, "Terms:")
    terms_y -= 13
    c.setFillColor(black)
    c.setFont("Helvetica", 9.5)
    c.drawString(margin_l, terms_y, "Pay by wire transfer:")
    terms_y -= 18
    c.drawString(margin_l, terms_y, f"IBAN CODE: {PAYMENT['iban']}")
    terms_y -= 12
    c.drawString(margin_l, terms_y, f"SWIFT CODE: {PAYMENT['swift']}")
    terms_y -= 18

    def draw_block(label: str, lines: list[str], y_start: int) -> int:
        c.setFillColor(GRAY)
        c.setFont("Helvetica", 9)
        c.drawString(margin_l, y_start, label)
        y_start -= 12
        c.setFillColor(black)
        c.setFont("Helvetica", 9.5)
        for ln in lines:
            c.drawString(margin_l, y_start, ln)
            y_start -= 12
        return y_start - 8

    terms_y = draw_block("Beneficary Name:", [PAYMENT["beneficiary_name"]], terms_y)
    terms_y = draw_block("Beneficary Address:", PAYMENT["beneficiary_address"], terms_y)
    terms_y = draw_block(
        "Beneficary Bank:",
        [PAYMENT["bank_name"], *PAYMENT["bank_address"]],
        terms_y,
    )

    c.showPage()
    c.save()


def main() -> int:
    try:
        inv = gather_inputs()
    except (KeyboardInterrupt, EOFError):
        print()
        return 130

    output_path = Path.cwd() / safe_filename(inv.number)
    render_pdf(inv, output_path)
    print()
    print(f"Wrote {output_path}")
    print(f"  Issue date: {fmt_date_long(inv.issue_date)}")
    print(f"  Due date:   {fmt_date_long(inv.due_date)}")
    print(f"  Total:      {fmt_money(inv.total_amount)}")
    return 0


if __name__ == "__main__":
    sys.exit(main())