alpha2-wasm 0.1.0

//! Project authoring helpers for the web, run by the same code natively:
//! subtitle import (SRT and WebVTT to caption-track cues), caption font
//! families, and project lint.

use alpha2_model::{ImportedCaptions, Project, caption_rows, parse_srt, parse_webvtt};
use wasm_bindgen::prelude::*;

use crate::web::{internal_error, invalid_input, typed_error};

/// Reads a subtitle file (`format` is `srt` or `webvtt`) into caption cues,
/// returned as JSON `{ rows, skipped }`.
///
/// `rows` holds one caption track's cues per row, each a project document
/// `CaptionCue`, split so no cue overlaps another in its row and no row holds
/// more cues than a caption track allows. `skipped` counts blocks that were
/// not cues.
///
/// # Errors
/// Rejects an unknown format, a WebVTT file without its header, and cues that
/// need more caption tracks than a project holds.
#[wasm_bindgen(js_name = parseCaptions)]
pub fn parse_captions(text: &str, format: &str) -> Result<String, JsValue> {
    let imported: ImportedCaptions = match format {
        "srt" => parse_srt(text).map_err(invalid_input)?,
        "webvtt" => parse_webvtt(text).map_err(invalid_input)?,
        other => {
            return Err(invalid_input(format!(
                "caption format must be srt or webvtt, not {other}"
            )));
        }
    };
    let rows = caption_rows(&imported.cues).map_err(invalid_input)?;
    serde_json::to_string(&serde_json::json!({
        "rows": rows,
        "skipped": imported.skipped,
    }))
    .map_err(internal_error)
}

/// Returns the family name a caption style's `font_family` must give to
/// select face `face_index` of the font file `bytes`, read from the font's
/// name table as the engine reads it; `undefined` when the bytes are not a
/// font or the face names no family.
#[wasm_bindgen(js_name = fontFamily)]
#[must_use]
pub fn font_family(bytes: &[u8], face_index: u32) -> Option<String> {
    alpha2_text::font_family(bytes, face_index)
}

/// Checks that `bytes` hold face `face_index` of a font the engine draws
/// captions and SVG text with, as registering it checks it.
///
/// # Errors
/// Rejects bytes the engine's font parser refuses, with its reason (a WOFF
/// or WOFF2 container named `.ttf`, say).
#[wasm_bindgen(js_name = checkFont)]
pub fn check_font(bytes: &[u8], face_index: u32) -> Result<(), JsValue> {
    alpha2_text::check_font(bytes, face_index).map_err(invalid_input)
}

/// A project's non-fatal diagnostics (`Project::lint`), as a JSON array of
/// issues (`alpha2/project`'s `LintIssue`).
///
/// # Errors
/// Rejects a document that does not load as a valid project.
#[wasm_bindgen(js_name = lintProject)]
pub fn lint_project(project_json: &str) -> Result<String, JsValue> {
    let project = Project::from_json(project_json).map_err(|error| typed_error(&error))?;
    serde_json::to_string(&project.lint()).map_err(internal_error)
}