Code 128 and retail barcodes

//! Writes a page of barcodes, drawn as bars: Code 128 for arbitrary text, an
//! EAN-13 for a thirteen-digit article number, a UPC-A for its twelve-digit
//! North American cousin, and a short EAN-8.
//!
//! Whether a barcode works is not a question the page can answer, and not one a
//! human eye can: it is answered by a scanner. So the page carries what each
//! barcode says under it, and `scripts/check_barcode.sh` points a decoder at
//! the rendered image and compares.
//!
//! The head of the sheet says what the bars are for, so that the page is worth
//! something to whoever opens it without the code beside it. Those words are
//! held in `Words`, once per language, and `HQF_PDF_LANG` picks which set the
//! sheet is headed in. What the barcodes carry stands apart from them: a
//! scanner reads it, not a person, and it is the same in every language.
//!
//! Usage: `cargo run --example write_barcode -- tmp/barcode.pdf [font.ttf]`
//!        `HQF_PDF_LANG=fr cargo run --example write_barcode --
//! tmp/barcode_fr.pdf`

use std::env;
use std::fs;
use std::path::{Path, PathBuf};

use hqf_pdf::barcode::QUIET_ZONE;
use hqf_pdf::content::Content;
use hqf_pdf::cos::Name;
use hqf_pdf::{Code128, Document, Ean8, Ean13, Error, Font, FontHandle, License, Page, UpcA};

#[path = "shared/out.rs"]
mod out;

#[path = "shared/licence.rs"]
mod licence;

#[path = "shared/language.rs"]
mod language;

use language::Language;

/// The font the example draws with when none is given on the command line.
fn default_font() -> PathBuf {
    Path::new(env!("CARGO_MANIFEST_DIR"))
        .join("tests")
        .join("fonts")
        .join("DejaVuSans.ttf")
}

/// What the Code 128 barcodes carry: an invoice number, a payment reference,
/// and a line holding every kind of character code set B carries.
const CARRIED: &[&str] = &["FR-1964413", "REF 2026-07-16/ACME", "a-Z 0..9 +*#%"];

/// The thirteen-digit article number the EAN-13 barcode carries.
const ARTICLE: &str = "9780201379624";

/// The twelve-digit article number the UPC-A barcode carries.
const UPC_ARTICLE: &str = "036000291452";

/// The eight-digit article number the EAN-8 barcode carries.
const EAN8_ARTICLE: &str = "96385074";

/// The width of the narrowest bar, in points. Everything else is a whole number
/// of these.
const MODULE: f64 = 1.0;

/// How tall the bars are drawn, in points.
const BAR_HEIGHT: f64 = 40.0;

/// Where the foot of the first barcode sits, in points up from the foot of the
/// sheet.
const TOP: f64 = 700.0;

/// How far in from the left edge of the sheet the head of the page is set. The
/// quiet zone of the first barcode starts here too, so the heading stands over
/// the left edge of the block of bars.
const MARGIN: f64 = 72.0;

/// Where the baseline of the heading sits, in points up from the foot of the
/// sheet.
const HEAD_TOP: f64 = 794.0;

/// The size the heading is set at, in points.
const HEADING: f64 = 16.0;

/// The size the lines under the heading are set at, in points.
const BODY: f64 = 10.5;

/// How far under the heading the first line beneath it sits, in points.
const HEAD_GAP: f64 = 24.0;

/// How far below one line under the heading the next one sits, in points.
const LINE_STEP: f64 = 15.0;

/// The words the sheet is headed in, one set per language.
#[derive(Debug)]
struct Words {
    /// What the page says it is, at its head and in what the file says of
    /// itself.
    title: &'static str,
    /// What the page says under its heading.
    lines: [&'static str; 2],
}

impl Words {
    /// The words the sheet is headed in, in `language`.
    fn of(language: Language) -> &'static Self {
        language::pick(&WORDS, language)
    }
}

/// The head of the sheet in English.
const ENGLISH: Words = Words {
    title: "Barcodes, drawn as bars",
    lines: [
        "Each barcode below is drawn as bars, not pasted in as a picture, so it prints",
        "exactly as wide as it should. Under each one is what a scanner reads back.",
    ],
};

/// The head of the sheet in French.
const FRENCH: Words = Words {
    title: "Des codes-barres, dessinés en barres",
    lines: [
        "Chaque code-barres ci-dessous est dessiné en barres, pas collé comme une image :",
        "il s'imprime à la largeur exacte. Sous chacun est écrit ce qu'un scanner y lit.",
    ],
};

/// Every language the example is written in. A language is added by writing its
/// own set of words and naming it here.
static WORDS: [(Language, &Words); 2] =
    [(Language::English, &ENGLISH), (Language::French, &FRENCH)];

/// The heading, and the lines under it that say what the page is for.
fn head(content: &mut Content, font: &FontHandle, words: &Words) -> Result<(), Error> {
    content.begin_text();
    content.set_font(font.name(), HEADING)?;
    content.text_origin(MARGIN, HEAD_TOP)?;
    content.show_glyphs(&font.glyphs(words.title));
    content.end_text();

    let mut y = HEAD_TOP - HEAD_GAP;
    for line in words.lines {
        content.begin_text();
        content.set_font(font.name(), BODY)?;
        content.text_origin(MARGIN, y)?;
        content.show_glyphs(&font.glyphs(line));
        content.end_text();
        y -= LINE_STEP;
    }
    Ok(())
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let language = Language::from_environment()?;
    let words = Words::of(language);

    let mut args: Vec<String> = env::args().skip(1).collect();
    let evaluation = args.iter().any(|arg| arg == "--evaluation");
    args.retain(|arg| !arg.starts_with("--"));

    let mut args = args.into_iter();
    // A named file is written as named; the default one carries the language,
    // so the two languages do not overwrite each other in `tmp/`.
    let path = args
        .next()
        .unwrap_or_else(|| language.file_name(&out::default_path("barcode")));
    let font_path = args.next().map_or_else(default_font, PathBuf::from);

    let mut doc = Document::new();
    doc.set_license(if evaluation {
        License::evaluation()
    } else {
        licence::licensed()
    });
    doc.set_info(Name::new("Title"), words.title);

    let font: FontHandle = doc.add_font(Font::parse(fs::read(&font_path)?)?);

    let mut content = Content::new();
    content.set_fill_rgb(0.0, 0.0, 0.0)?;
    head(&mut content, &font, words)?;

    let mut top = TOP;
    for carried in CARRIED {
        let code = Code128::new(carried)?;

        // The quiet zone is the caller's: the bars start ten modules in, and
        // nothing else is drawn beside them.
        let left = f64::from(u32::try_from(QUIET_ZONE)?).mul_add(MODULE, MARGIN);
        let width = f64::from(u32::try_from(code.module_count())?) * MODULE;
        content.draw_barcode(&code, left, top, width, BAR_HEIGHT)?;

        content.begin_text();
        content.set_font(font.name(), 9.0)?;
        content.text_origin(left, top - 12.0)?;
        content.show_glyphs(&font.glyphs(carried));
        content.end_text();

        top -= 120.0;
    }

    let left = f64::from(u32::try_from(QUIET_ZONE)?).mul_add(MODULE, MARGIN);

    let ean = Ean13::new(ARTICLE)?;
    let width = f64::from(u32::try_from(ean.module_count())?) * MODULE;
    content.draw_ean13(&ean, left, top, width, BAR_HEIGHT)?;
    content.begin_text();
    content.set_font(font.name(), 9.0)?;
    content.text_origin(left, top - 12.0)?;
    content.show_glyphs(&font.glyphs(ARTICLE));
    content.end_text();
    top -= 120.0;

    let upc = UpcA::new(UPC_ARTICLE)?;
    let width = f64::from(u32::try_from(upc.module_count())?) * MODULE;
    content.draw_upc_a(&upc, left, top, width, BAR_HEIGHT)?;
    content.begin_text();
    content.set_font(font.name(), 9.0)?;
    content.text_origin(left, top - 12.0)?;
    content.show_glyphs(&font.glyphs(UPC_ARTICLE));
    content.end_text();
    top -= 120.0;

    let ean8 = Ean8::new(EAN8_ARTICLE)?;
    let width = f64::from(u32::try_from(ean8.module_count())?) * MODULE;
    content.draw_ean8(&ean8, left, top, width, BAR_HEIGHT)?;
    content.begin_text();
    content.set_font(font.name(), 9.0)?;
    content.text_origin(left, top - 12.0)?;
    content.show_glyphs(&font.glyphs(EAN8_ARTICLE));
    content.end_text();

    let mut page = Page::a4();
    page.content = content.into_bytes();
    doc.add_page(page)?;

    let bytes = doc.to_bytes()?;
    if let Some(parent) = Path::new(&path).parent() {
        fs::create_dir_all(parent)?;
    }
    fs::write(&path, &bytes)?;
    println!("wrote {} ({} bytes)", path, bytes.len());
    Ok(())
}

#[cfg(test)]
mod tests {
    use hqf_pdf::{Document, Font};

    use super::{
        BAR_HEIGHT, BODY, HEAD_GAP, HEAD_TOP, HEADING, LINE_STEP, MARGIN, TOP, WORDS, default_font,
        language,
    };

    /// The width of the sheet, in points: A4, which the page is.
    const SHEET_WIDTH: f64 = 595.276;

    /// The lines two languages are allowed to write the same way. The heading
    /// and the lines under it are the whole of `Words`, and no two languages
    /// write one alike; what the barcodes carry is read by a scanner rather
    /// than by a person, so it stands apart from them.
    const SPARED: [&str; 0] = [];

    /// The room a line set from the left margin has before it reaches the
    /// margin on the other side of the sheet.
    const PAPER: f64 = SHEET_WIDTH - 2.0 * MARGIN;

    #[test]
    fn every_language_heads_the_sheet_in_its_own_words() {
        let untranslated = language::untranslated_lines(&WORDS, &SPARED);

        assert!(
            untranslated.is_empty(),
            "the sheet says these in more than one language: {untranslated:?}"
        );
    }

    /// Nothing at the head of the sheet is broken to a width: a line longer
    /// than the paper runs off the edge of it.
    #[test]
    fn every_language_writes_lines_that_fit_the_room_they_have() {
        let mut doc = Document::new();
        let text = doc.add_font(
            Font::parse(std::fs::read(default_font()).expect("the committed font is there"))
                .expect("the committed font parses"),
        );

        for (named, words) in WORDS {
            let code = named.code();
            let lines =
                std::iter::once((HEADING, words.title)).chain(words.lines.map(|line| (BODY, line)));

            for (size, line) in lines {
                let measured = text.measure(line, size);
                assert!(
                    measured <= PAPER,
                    "the {code} sheet draws {line:?} over {measured:.1} points, \
                     and it has {PAPER:.1}"
                );
            }
        }
    }

    /// The head of the sheet is set above the bars, and the bars start where
    /// the first barcode is drawn. A line too many at the head would be drawn
    /// over them.
    #[test]
    fn the_head_of_the_sheet_stands_clear_of_the_bars() {
        let bars = TOP + BAR_HEIGHT;

        for (named, words) in WORDS {
            let count = u32::try_from(words.lines.len()).expect("a head has few lines");
            let last = LINE_STEP.mul_add(-f64::from(count - 1), HEAD_TOP - HEAD_GAP);
            assert!(
                last - BODY >= bars,
                "the {} head ends on a line at {last:.1} points, and the bars \
                 reach {bars:.1}",
                named.code()
            );
        }
    }
}