"""
Test helpers for e2e tests — generate in-memory test files.

All helpers return raw bytes suitable for use with page.set_input_files().
"""

from __future__ import annotations

import io
import struct
import zlib


def create_test_image(width: int = 64, height: int = 64) -> bytes:
    """Generate a minimal valid PNG image in memory.

    Returns raw PNG bytes. Does not require Pillow — builds a PNG manually
    using only the stdlib so that helpers.py has zero external dependencies.
    """
    # PNG signature
    png_sig = b"\x89PNG\r\n\x1a\n"

    def make_chunk(chunk_type: bytes, data: bytes) -> bytes:
        length = struct.pack(">I", len(data))
        crc = struct.pack(">I", zlib.crc32(chunk_type + data) & 0xFFFFFFFF)
        return length + chunk_type + data + crc

    # IHDR: width, height, bit depth=8, color type=2 (RGB), compression=0,
    # filter=0, interlace=0
    ihdr_data = struct.pack(">IIBBBBB", width, height, 8, 2, 0, 0, 0)
    ihdr = make_chunk(b"IHDR", ihdr_data)

    # IDAT: raw scanlines (filter byte 0 per row, then RGB pixels)
    raw_rows = []
    for y in range(height):
        row = b"\x00"  # filter type None
        for x in range(width):
            # Vary pixel color so the image is non-trivial
            r = (x * 4) & 0xFF
            g = (y * 4) & 0xFF
            b = ((x + y) * 2) & 0xFF
            row += bytes([r, g, b])
        raw_rows.append(row)

    compressed = zlib.compress(b"".join(raw_rows))
    idat = make_chunk(b"IDAT", compressed)

    iend = make_chunk(b"IEND", b"")

    return png_sig + ihdr + idat + iend


def create_test_pdf() -> bytes:
    """Generate a minimal valid single-page PDF in memory.

    The PDF is structurally valid (Acrobat/browsers will accept it) but
    contains only a blank page with a text label.
    """
    body = b"""%PDF-1.4
1 0 obj<</Type/Catalog/Pages 2 0 R>>endobj
2 0 obj<</Type/Pages/Kids[3 0 R]/Count 1>>endobj
3 0 obj<</Type/Page/MediaBox[0 0 612 792]/Parent 2 0 R/Resources<</Font<</F1 4 0 R>>>>>>endobj
4 0 obj<</Type/Font/Subtype/Type1/BaseFont/Helvetica>>endobj
5 0 obj<</Length 44>>
stream
BT /F1 12 Tf 100 700 Td (FieldWitness test PDF) Tj ET
endstream
endobj
"""
    xref_offset = len(body)
    body += (
        b"xref\n"
        b"0 6\n"
        b"0000000000 65535 f \n"
        b"0000000009 00000 n \n"
        b"0000000058 00000 n \n"
        b"0000000115 00000 n \n"
        b"0000000266 00000 n \n"
        b"0000000346 00000 n \n"
        b"trailer<</Size 6/Root 1 0 R>>\n"
        b"startxref\n"
    )
    body += str(xref_offset).encode() + b"\n%%EOF\n"
    return body


def create_test_csv() -> bytes:
    """Generate a simple CSV file in memory."""
    lines = [
        "timestamp,sensor_id,value,unit",
        "2024-01-15T10:00:00Z,TEMP-001,23.5,celsius",
        "2024-01-15T10:01:00Z,TEMP-001,23.7,celsius",
        "2024-01-15T10:02:00Z,TEMP-001,23.6,celsius",
        "2024-01-15T10:03:00Z,HUMID-001,65.2,percent",
    ]
    return "\n".join(lines).encode("utf-8")


def create_test_txt() -> bytes:
    """Generate a plain-text file in memory."""
    content = (
        "FieldWitness e2e test document\n"
        "===============================\n\n"
        "This file was generated by the automated test suite.\n"
        "It contains no sensitive information.\n"
    )
    return content.encode("utf-8")