//! The hostile-case table for `Annotations::from_json`: one case per validation rule.

use std::fmt::Write as _;

use notescraft_annotate::{Annotations, Error};

/// What a hostile case must produce.
#[derive(Debug, Clone, Copy, PartialEq)]
enum Kind {
    Version(u64),
    TooManyItems,
    TooManyStrokePoints,
    TooManyTotalPoints,
    NonFinite,
    OutOfRange,
    BadWidth,
    BadText,
    UnknownType,
    UnknownKey,
    TooLarge,
    TooDeep,
    ImageChanged(u32, u32),
    BadField,
}

/// Does the error match the expectation?
fn same(error: &Error, want: &Kind) -> bool {
    match want {
        Kind::Version(found) => matches!(error, Error::Version(seen) if seen == found),
        Kind::ImageChanged(w, h) => matches!(
            error,
            Error::ImageChanged { stored_w, stored_h, .. } if (*stored_w, *stored_h) == (*w, *h)
        ),
        _ => matches!(
            (error, want),
            (Error::TooManyItems(_), Kind::TooManyItems)
                | (Error::TooManyStrokePoints(_), Kind::TooManyStrokePoints)
                | (Error::TooManyTotalPoints(_), Kind::TooManyTotalPoints)
                | (Error::NonFinite, Kind::NonFinite)
                | (Error::OutOfRange { .. }, Kind::OutOfRange)
                | (Error::BadWidth(_), Kind::BadWidth)
                | (Error::BadText(_), Kind::BadText)
                | (Error::UnknownType(_), Kind::UnknownType)
                | (Error::UnknownKey { .. }, Kind::UnknownKey)
                | (Error::TooLarge(_), Kind::TooLarge)
                | (Error::TooDeep(_), Kind::TooDeep)
                | (Error::BadField, Kind::BadField)
        ),
    }
}

/// A document with the given items verbatim into an image of 1000x800.
fn doc(items: &str) -> String {
    format!("{{\"version\":1,\"image\":{{\"hash\":null,\"width\":1000,\"height\":800}},\"items\":[{items}]}}")
}

/// One stroke with the given verbatim points and width.
fn stroke(points: &str, width: &str) -> String {
    format!("{{\"type\":\"stroke\",\"tool\":\"pen\",\"color\":{{\"theme\":0}},\"width\":{width},\"points\":[{points}]}}")
}

/// A comma-joined run of `[x, y]` pairs along a diagonal.
fn points_run(count: usize) -> String {
    let mut string = String::new();
    for index in 0..count {
        if index > 0 {
            string.push(',');
        }
        let (x, y) = (u64::try_from(index % 900).unwrap_or(0), u64::try_from(index % 700).unwrap_or(0));
        if write!(string, "[{x},{y}]").is_err() {
            return string;
        }
    }
    string
}

/// A valid text item, with a `text` field patched in.
fn text_item(text_field: &str) -> String {
    format!("{{\"type\":\"text\",\"color\":{{\"theme\":0}},\"size\":2.0,\"at\":[0,0],\"text\":{text_field}}}")
}

#[test]
fn validation_refuses_each_hostile_case() {
    let too_long_text = format!("\"{}\"", "a".repeat(2001));
    let nine_mib_junk = " ".repeat(9 * 1024 * 1024);
    let nine_mib = format!("{{\"version\":1,\"image\":{{\"hash\":null,\"width\":1000,\"height\":800}},\"items\":[],\"junk\":\"{nine_mib_junk}\"}}");
    let cases: Vec<(&str, String, Kind)> = vec![
        ("version 2", doc("").replace("\"version\":1", "\"version\":2"), Kind::Version(2)),
        ("missing version", doc("").replace("\"version\":1,", ""), Kind::Version(0)),
        ("one item over the cap", doc(&(0..5001).map(|_| text_item("\"x\"")).collect::<Vec<_>>().join(",")), Kind::TooManyItems),
        ("stroke over the point cap", doc(&stroke(&points_run(20_001), "2.0")), Kind::TooManyStrokePoints),
        ("total over the point cap", doc(&(0..11).map(|_| stroke(&points_run(20_000), "2.0")).collect::<Vec<_>>().join(",")), Kind::TooManyTotalPoints),
        ("x as NaN string", doc(&stroke("[\"NaN\",0]", "2.0")), Kind::NonFinite),
        ("y as infinity string", doc(&stroke("[0,\"Infinity\"]", "2.0")), Kind::NonFinite),
        ("x over 5w", doc(&stroke("[5001,0]", "2.0")), Kind::OutOfRange),
        ("y under -4h", doc(&stroke("[0,-3201]", "2.0")), Kind::OutOfRange),
        ("width under the range", doc(&stroke("[0,0]", "0.4")), Kind::BadWidth),
        ("size over the range", doc(&text_item("\"x\"").replace("\"size\":2.0", "\"size\":200.1")), Kind::BadWidth),
        ("text too long", doc(&text_item(&too_long_text)), Kind::BadText),
        ("text with control char", doc(&text_item("\"a\\u0007b\"")), Kind::BadText),
        ("unknown type", doc("{\"type\":\"stamp\",\"color\":{\"theme\":0}}"), Kind::UnknownType),
        (
            "unknown key inside stroke",
            doc("{\"type\":\"stroke\",\"tool\":\"pen\",\"color\":{\"theme\":0},\"width\":2.0,\"alpha\":1,\"points\":[[0,0]]}"),
            Kind::UnknownKey,
        ),
        ("nine mebibytes", nine_mib, Kind::TooLarge),
        ("depth 40", "[".repeat(40) + &"]".repeat(40), Kind::TooDeep),
        ("array root", "[1,2,3]".to_string(), Kind::BadField),
        ("missing items", doc("").replace(",\"items\":[]", ""), Kind::BadField),
        (
            "size mismatch without a hash",
            "{\"version\":1,\"image\":{\"hash\":null,\"width\":500,\"height\":400},\"items\":[]}".to_string(),
            Kind::ImageChanged(500, 400),
        ),
    ];
    for (name, document, want) in cases {
        match Annotations::from_json(&document, 1000, 800) {
            Ok(_) => panic!("accepted: {name}"),
            Err(error) => assert!(same(&error, &want), "{name}: got {error:?}, want {want:?}"),
        }
    }
}

/// A hash vouches for a stored size that differs from the actual image.
#[test]
fn validation_tolerates_size_mismatch_when_hashed() {
    let vouched = "{\"version\":1,\"image\":{\"hash\":\"abc\",\"width\":500,\"height\":400},\"items\":[]}";
    let notes = Annotations::from_json(vouched, 1000, 800).unwrap();
    assert_eq!((notes.image.width, notes.image.height), (500, 400));
    assert_eq!(notes.image.hash.as_deref(), Some("abc"));
}

/// A new-line inside a text label is legal.
#[test]
fn validation_allows_newline_in_text() {
    let document = doc(&text_item("\"a\\nb\""));
    let notes = Annotations::from_json(&document, 1000, 800).unwrap();
    assert_eq!(notes.items.len(), 1);
}