//! `Session::pdf_preview`: a page image from the system's renderer, cached in the vault.

mod common;

use common::temp_vault;
use notescraft_engine::Session;

/// A one-page PDF with a line of text.
const PDF: &str = "%PDF-1.1\n1 0 obj<</Type/Catalog/Pages 2 0 R>>endobj\n2 0 obj<</Type/Pages/Kids[3 0 R]/Count 1>>endobj\n3 0 obj<</Type/Page/Parent 2 0 R/MediaBox[0 0 200 100]/Contents 4 0 R/Resources<</Font<</F1 5 0 R>>>>>>endobj\n4 0 obj<</Length 44>>stream\nBT /F1 24 Tf 20 40 Td (Hello) Tj ET\nendstream\nendobj\n5 0 obj<</Type/Font/Subtype/Type1/BaseFont/Helvetica>>endobj\ntrailer<</Root 1 0 R>>\n%%EOF\n";

#[test]
fn a_pdf_page_becomes_a_cached_png_or_a_clear_error() {
    let vault = temp_vault("pdf-preview");
    std::fs::write(vault.path().join("doc.pdf"), PDF).expect("write");
    let session = Session::open(vault.path()).expect("open");
    assert!(session.pdf_preview("doc.pdf", 0).is_err(), "page numbers start at 1");
    assert!(session.pdf_preview("../outside.pdf", 1).is_err());
    match session.pdf_preview("doc.pdf", 1) {
        Ok(png) => {
            assert!(png.starts_with(b"\x89PNG"), "a PNG came back");
            let cached = std::fs::read_dir(vault.path().join(".notescraft/cache")).expect("cache").count();
            assert!(cached >= 1, "the image is cached");
            assert_eq!(session.pdf_preview("doc.pdf", 1).expect("again"), png, "the second call reads the cache");
        }
        Err(error) => eprintln!("no PDF renderer on this machine: {error}"),
    }
}

/// A two-page PDF: page 2 says "Second".
const TWO_PAGES: &str = "%PDF-1.1\n1 0 obj<</Type/Catalog/Pages 2 0 R>>endobj\n2 0 obj<</Type/Pages/Kids[3 0 R 6 0 R]/Count 2>>endobj\n3 0 obj<</Type/Page/Parent 2 0 R/MediaBox[0 0 200 100]/Contents 4 0 R/Resources<</Font<</F1 5 0 R>>>>>>endobj\n4 0 obj<</Length 44>>stream\nBT /F1 24 Tf 20 40 Td (First) Tj ET\nendstream\nendobj\n5 0 obj<</Type/Font/Subtype/Type1/BaseFont/Helvetica>>endobj\n6 0 obj<</Type/Page/Parent 2 0 R/MediaBox[0 0 300 200]/Contents 7 0 R/Resources<</Font<</F1 5 0 R>>>>>>endobj\n7 0 obj<</Length 45>>stream\nBT /F1 24 Tf 20 40 Td (Second) Tj ET\nendstream\nendobj\ntrailer<</Root 1 0 R>>\n%%EOF\n";

#[test]
fn the_page_asked_for_is_the_page_rendered() {
    let vault = temp_vault("pdf-pages");
    std::fs::write(vault.path().join("two.pdf"), TWO_PAGES).expect("write");
    let session = Session::open(vault.path()).expect("open");
    let (Ok(first), Ok(second)) = (session.pdf_preview("two.pdf", 1), session.pdf_preview("two.pdf", 2)) else {
        eprintln!("no PDF renderer able to pick a page on this machine");
        return;
    };
    assert_ne!(first, second, "page 2 is a different image (it is also a different size)");
    assert!(session.pdf_preview("two.pdf", 3).is_err(), "a page past the end is an error");
}