feat: implement cbz writing and pdf reading

tests/cbz_writer_tests.rs

@@ -0,0 +1,96 @@
+use std::fs::File;
+use std::io::Read;
+
+use cbz2pdf::formats::cbz::CbzWriter;
+use cbz2pdf::formats::FormatWriter;
+use cbz2pdf::model::{Document, ImagePage};
+
+fn make_tiny_jpeg() -> (Vec<u8>, image::DynamicImage) {
+    let img = image::DynamicImage::new_rgb8(1, 1).to_rgb8();
+    let mut buf = Vec::new();
+    {
+        let mut cursor = std::io::Cursor::new(&mut buf);
+        let mut enc = image::codecs::jpeg::JpegEncoder::new_with_quality(&mut cursor, 80);
+        enc.encode(&img, 1, 1, image::ColorType::Rgb8.into())
+            .unwrap();
+    }
+    let decoded = image::load_from_memory(&buf).unwrap();
+    (buf, decoded)
+}
+
+#[test]
+fn cbz_writer_preserves_dct_and_renames_non_jpg() {
+    // Prepare a page with original JPEG DCT data but a non-jpg name.
+    let (jpeg_dct, decoded) = make_tiny_jpeg();
+    let page = ImagePage {
+        name: "cover.png".to_string(),
+        image: decoded,
+        jpeg_dct: Some(jpeg_dct.clone()),
+    };
+    let doc = Document::new(vec![page]);
+
+    let temp_dir = tempfile::tempdir().expect("create temp dir");
+    let cbz_path = temp_dir.path().join("out.cbz");
+
+    let writer = CbzWriter;
+    writer.write(&doc, &cbz_path).expect("write cbz");
+
+    // Open the CBZ and verify it contains 001.jpg with the exact JPEG data.
+    let f = File::open(&cbz_path).unwrap();
+    let mut zip = zip::ZipArchive::new(f).unwrap();
+
+    // There should be exactly one file named 001.jpg
+    let mut found = false;
+    for i in 0..zip.len() {
+        let mut file = zip.by_index(i).unwrap();
+        let name = file.enclosed_name().unwrap().to_owned();
+        if name.file_name().unwrap() == "001.jpg" {
+            let mut data = Vec::new();
+            file.read_to_end(&mut data).unwrap();
+            assert_eq!(
+                data, jpeg_dct,
+                "writer should preserve original JPEG DCT bytes"
+            );
+            found = true;
+        }
+    }
+    assert!(found, "001.jpg not found in zip");
+}
+
+#[test]
+fn cbz_writer_keeps_jpg_name() {
+    // If the page already has a .jpg name, the writer should keep it.
+    let (jpeg_dct, decoded) = make_tiny_jpeg();
+    let page = ImagePage {
+        name: "page01.jpg".to_string(),
+        image: decoded,
+        jpeg_dct: Some(jpeg_dct),
+    };
+    let doc = Document::new(vec![page]);
+
+    let temp_dir = tempfile::tempdir().expect("create temp dir");
+    let cbz_path = temp_dir.path().join("out.cbz");
+
+    let writer = CbzWriter;
+    writer.write(&doc, &cbz_path).expect("write cbz");
+
+    let f = File::open(&cbz_path).unwrap();
+    let mut zip = zip::ZipArchive::new(f).unwrap();
+
+    let mut names = Vec::new();
+    for i in 0..zip.len() {
+        let file = zip.by_index(i).unwrap();
+        let name = file
+            .enclosed_name()
+            .unwrap()
+            .file_name()
+            .unwrap()
+            .to_owned();
+        names.push(name.to_string_lossy().to_string());
+    }
+    assert_eq!(
+        names,
+        vec!["page01.jpg"],
+        "existing .jpg name should be kept"
+    );
+}