[tablify] / src / lib.rs

use std::borrow::ToOwned;
use std::collections::HashMap;
use std::fmt::Write;
use std::io::BufRead;
use std::iter::Iterator;

#[derive(PartialEq, Eq, Debug)]
struct Config {
    column_threshold: usize,
}
impl Config {
    fn apply_command(&mut self, cmd: &str) -> Result<(), std::io::Error> {
        if let Some(threshold) = cmd.strip_prefix("col_threshold ") {
            self.column_threshold = threshold
                .parse()
                .map_err(|e| std::io::Error::new(std::io::ErrorKind::InvalidInput, e))?;
        }
        Ok(())
    }
}

const HEADER: &str = r#"<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <style>
    td { text-align: center; }
    /* h/t https://wabain.github.io/2019/10/13/css-rotated-table-header.html */
    th, td { white-space: nowrap; }
    th { text-align: left; font-weight: normal; }
    th.spacer_row { height: .3em; }
    table { border-collapse: collapse }
    tr.key > th { height: 10em; vertical-align: bottom; line-height: 1 }
    tr.key > th > div { width: 1em; }
    tr.key > th > div > div { width: 5em; transform-origin: bottom left; transform: translateX(1em) rotate(-65deg) }
    td { border: thin solid gray; }
    td.leftover { text-align: left; border: none; padding-left: .4em; }
    td.yes { border: thin solid gray; background-color: #ddd; }
    /* h/t https://stackoverflow.com/questions/5687035/css-bolding-some-text-without-changing-its-containers-size/46452396#46452396 */
    .highlight { text-shadow: -0.06ex 0 black, 0.06ex 0 black; }
  </style>
  <script>
    function highlight(id)       { const e = document.getElementById(id); if (e) { e.classList.add(   "highlight"); } }
    function clear_highlight(id) { const e = document.getElementById(id); if (e) { e.classList.remove("highlight"); } }
    function h2(a, b)  {       highlight(a);       highlight(b); }
    function ch2(a, b) { clear_highlight(a); clear_highlight(b); }
  </script>
</head>
<body>
  <table>
    <tbody>
"#;
const FOOTER: &str = "    </tbody>
  </table>
</body>
</html>";

#[derive(PartialEq, Eq, Debug)]
pub struct HTML(String);
impl HTML {
    fn escape(value: &str) -> HTML {
        let mut escaped: String = String::new();
        for c in value.chars() {
            match c {
                '>' => escaped.push_str("&gt;"),
                '<' => escaped.push_str("&lt;"),
                '\'' => escaped.push_str("&#39;"),
                '"' => escaped.push_str("&quot;"),
                '&' => escaped.push_str("&amp;"),
                ok_c => escaped.push(ok_c),
            }
        }
        HTML(escaped)
    }
}
impl From<&str> for HTML {
    fn from(value: &str) -> HTML {
        HTML(String::from(value))
    }
}
impl FromIterator<HTML> for HTML {
    fn from_iter<T>(iter: T) -> HTML
    where
        T: IntoIterator<Item = HTML>,
    {
        HTML(iter.into_iter().map(|html| html.0).collect::<String>())
    }
}
impl std::fmt::Display for HTML {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.0)
    }
}

#[derive(Debug, PartialEq, Eq)]
enum InputLine<'a> {
    Blank,
    RowHeader(&'a str),
    Entry(&'a str, Option<&'a str>),
    Command(&'a str),
}
impl<'a> From<&'a str> for InputLine<'a> {
    fn from(value: &'a str) -> InputLine<'a> {
        let trimmed = value.trim_end();
        if trimmed.is_empty() {
            InputLine::Blank
        } else if let Some(cmd) = trimmed.strip_prefix('!') {
            InputLine::Command(cmd)
        } else if !trimmed.starts_with(' ') {
            InputLine::RowHeader(value.trim())
        } else {
            match value.split_once(':') {
                None => InputLine::Entry(value.trim(), None),
                Some((col, instance)) => InputLine::Entry(col.trim(), Some(instance.trim())),
            }
        }
    }
}

#[derive(Debug, PartialEq, Eq)]
struct Row {
    label: String,
    entries: HashMap<String, Vec<Option<String>>>,
}

#[derive(Debug, PartialEq, Eq)]
enum Rowlike {
    Row(Row),
    Spacer,
}

struct Reader<'cfg, Input: Iterator<Item = Result<String, std::io::Error>>> {
    input: std::iter::Enumerate<Input>,
    row: Option<Row>,
    config: &'cfg mut Config,
}
impl<'cfg, Input: Iterator<Item = Result<String, std::io::Error>>> Reader<'cfg, Input> {
    fn new(config: &'cfg mut Config, input: Input) -> Self {
        Self {
            input: input.enumerate(),
            row: None,
            config,
        }
    }
}
impl<'cfg, Input: Iterator<Item = Result<String, std::io::Error>>> Iterator
    for Reader<'cfg, Input>
{
    type Item = Result<Rowlike, std::io::Error>;
    fn next(&mut self) -> Option<Self::Item> {
        loop {
            match self.input.next() {
                None => return Ok(std::mem::take(&mut self.row).map(Rowlike::Row)).transpose(),
                Some((_, Err(e))) => return Some(Err(e)),
                Some((n, Ok(line))) => match InputLine::from(line.as_ref()) {
                    InputLine::Command(cmd) => {
                        if let Err(e) = self.config.apply_command(cmd) {
                            return Some(Err(e));
                        }
                    }
                    InputLine::Blank if self.row.is_some() => {
                        return Ok(std::mem::take(&mut self.row).map(Rowlike::Row)).transpose()
                    }
                    InputLine::Blank => return Some(Ok(Rowlike::Spacer)),
                    InputLine::Entry(col, instance) => match &mut self.row {
                        None => {
                            return Some(Err(std::io::Error::other(format!(
                                "{}: Entry with no header",
                                n + 1
                            ))))
                        }
                        Some(ref mut row) => {
                            row.entries
                                .entry(col.to_owned())
                                .and_modify(|is| is.push(instance.map(ToOwned::to_owned)))
                                .or_insert_with(|| vec![instance.map(ToOwned::to_owned)]);
                        }
                    },
                    InputLine::RowHeader(row) => {
                        let prev = std::mem::take(&mut self.row);
                        self.row = Some(Row {
                            label: row.to_owned(),
                            entries: HashMap::new(),
                        });
                        if prev.is_some() {
                            return Ok(prev.map(Rowlike::Row)).transpose();
                        }
                    }
                },
            }
        }
    }
}

fn read_input(input: impl std::io::Read) -> Result<(Vec<Rowlike>, Config), std::io::Error> {
    let mut config = Config {
        column_threshold: 2,
    };
    let reader = Reader::new(&mut config, std::io::BufReader::new(input).lines());
    reader
        .collect::<Result<Vec<_>, _>>()
        .map(|rows| (rows, config))
}

fn column_counts(rows: &[Rowlike]) -> Vec<(usize, String)> {
    let empty = HashMap::new();
    let mut counts: Vec<_> = rows
        .iter()
        .flat_map(|rl| match rl {
            Rowlike::Row(r) => r.entries.keys(),
            Rowlike::Spacer => empty.keys(),
        })
        .fold(HashMap::new(), |mut cs, col| {
            cs.entry(col.to_owned())
                .and_modify(|n| *n += 1)
                .or_insert(1);
            cs
        })
        .into_iter()
        .map(|(col, n)| (n, col))
        .collect();
    counts.sort_unstable_by(|(an, acol), (bn, bcol)| bn.cmp(an).then(acol.cmp(bcol)));
    counts
}
fn column_order(config: &Config, rows: &[Rowlike]) -> Vec<String> {
    column_counts(rows)
        .into_iter()
        .filter_map(|(n, col)| (n >= config.column_threshold).then_some(col))
        .collect()
}

fn render_one_instance(instance: &Option<String>) -> HTML {
    match instance {
        None => HTML::from("✓"),
        Some(instance) => HTML::escape(instance.as_ref()),
    }
}

fn render_instances(instances: &[Option<String>]) -> HTML {
    let all_empty = instances.iter().all(Option::is_none);
    if all_empty && instances.len() == 1 {
        HTML::from("")
    } else if all_empty {
        HTML(format!("{}", instances.len()))
    } else {
        HTML(
            instances
                .iter()
                .map(render_one_instance)
                .map(|html| html.0) // Waiting for slice_concat_trait to stabilize
                .collect::<Vec<_>>()
                .join(" "),
        )
    }
}

fn render_cell(col: &str, row: &mut Row) -> HTML {
    let row_label = HTML::escape(row.label.as_ref());
    let col_label = HTML::escape(col);
    let instances: Option<&Vec<Option<String>>> = row.entries.get(col);
    let class = HTML::from(if instances.is_none() { "" } else { "yes" });
    let contents = match instances {
        None => HTML::from(""),
        Some(is) => render_instances(is),
    };
    row.entries.remove(col);
    HTML(format!(
        r#"<td class="{class}" onmouseover="h2('{row_label}','{col_label}')" onmouseout="ch2('{row_label}','{col_label}')">{contents}</td>"#
    ))
}

fn render_leftover(notcol: &str, instances: &[Option<String>]) -> HTML {
    let label = HTML::escape(notcol);
    let rest = render_instances(instances);
    if rest == HTML::from("") {
        HTML(format!("{label}"))
    } else {
        HTML(format!("{label}: {rest}"))
    }
}

fn render_all_leftovers(row: &Row) -> HTML {
    let mut order: Vec<_> = row.entries.keys().collect();
    order.sort_unstable();
    HTML(
        order
            .into_iter()
            .map(|notcol| render_leftover(notcol, row.entries.get(notcol).expect("Key vanished?!")))
            .map(|html| html.0) // Waiting for slice_concat_trait to stabilize
            .collect::<Vec<_>>()
            .join(", "),
    )
}

fn render_row(columns: &[String], rowlike: &mut Rowlike) -> HTML {
    match rowlike {
        Rowlike::Spacer => HTML::from("<tr><th class=\"spacer_row\"></th></tr>\n"),
        Rowlike::Row(row) => {
            let row_label = HTML::escape(row.label.as_ref());
            let cells = columns
                .iter()
                .map(|col| render_cell(col, row))
                .collect::<HTML>();
            let leftovers = render_all_leftovers(row);
            HTML(format!(
                "<tr><th id=\"{row_label}\">{row_label}</th>{cells}<td class=\"leftover\" onmouseover=\"highlight('{row_label}')\" onmouseout=\"clear_highlight('{row_label}')\">{leftovers}</td></tr>\n"
            ))
        }
    }
}

fn render_column_headers(columns: &[String]) -> HTML {
    HTML(
        String::from(r#"<tr class="key"><th></th>"#)
            + &columns.iter().fold(String::new(), |mut acc, col| {
                let col_header = HTML::escape(col.as_ref());
                write!(
                    &mut acc,
                    r#"<th id="{col_header}"><div><div>{col_header}</div></div></th>"#
                )
                .unwrap();
                acc
            })
            + "</tr>\n",
    )
}

/// # Errors
///
/// Will return `Err` if
///   * there's an i/o error while reading `input`
///   * the log has invalid syntax:
///     * an indented line with no preceding non-indented line
pub fn tablify(input: impl std::io::Read) -> Result<HTML, std::io::Error> {
    let (rows, config) = read_input(input)?;
    let columns = column_order(&config, &rows);
    Ok(HTML(format!(
        "{HEADER}{}{}{FOOTER}",
        render_column_headers(&columns),
        rows.into_iter()
            .map(|mut r| render_row(&columns, &mut r))
            .collect::<HTML>()
    )))
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_parse_line() {
        assert_eq!(InputLine::from(""), InputLine::Blank);
        assert_eq!(InputLine::from(" "), InputLine::Blank);
        assert_eq!(InputLine::from("foo"), InputLine::RowHeader("foo"));
        assert_eq!(InputLine::from("foo "), InputLine::RowHeader("foo"));
        assert_eq!(InputLine::from(" foo"), InputLine::Entry("foo", None));
        assert_eq!(
            InputLine::from(" foo:bar"),
            InputLine::Entry("foo", Some("bar"))
        );
        assert_eq!(
            InputLine::from(" foo: bar"),
            InputLine::Entry("foo", Some("bar"))
        );
        assert_eq!(
            InputLine::from(" foo: bar "),
            InputLine::Entry("foo", Some("bar"))
        );
        assert_eq!(
            InputLine::from(" foo:  bar "),
            InputLine::Entry("foo", Some("bar"))
        );
        assert_eq!(
            InputLine::from(" foo :  bar "),
            InputLine::Entry("foo", Some("bar"))
        );
    }

    fn read_rows(input: impl std::io::Read) -> Result<Vec<Rowlike>, std::io::Error> {
        read_input(input).map(|(rows, _)| rows)
    }
    fn read_config(input: impl std::io::Read) -> Result<Config, std::io::Error> {
        read_input(input).map(|(_, config)| config)
    }
    #[test]
    fn test_read_rows() {
        assert_eq!(
            read_rows(&b"foo"[..]).unwrap(),
            vec![Rowlike::Row(Row {
                label: "foo".to_owned(),
                entries: HashMap::new(),
            })]
        );
        assert_eq!(
            read_rows(&b"bar"[..]).unwrap(),
            vec![Rowlike::Row(Row {
                label: "bar".to_owned(),
                entries: HashMap::new(),
            })]
        );
        assert_eq!(
            read_rows(&b"foo\nbar\n"[..]).unwrap(),
            vec![
                Rowlike::Row(Row {
                    label: "foo".to_owned(),
                    entries: HashMap::new(),
                }),
                Rowlike::Row(Row {
                    label: "bar".to_owned(),
                    entries: HashMap::new(),
                })
            ]
        );
        assert_eq!(
            read_rows(&b"foo\n bar\n"[..]).unwrap(),
            vec![Rowlike::Row(Row {
                label: "foo".to_owned(),
                entries: HashMap::from([("bar".to_owned(), vec![None])]),
            })]
        );
        assert_eq!(
            read_rows(&b"foo\n bar\n baz\n"[..]).unwrap(),
            vec![Rowlike::Row(Row {
                label: "foo".to_owned(),
                entries: HashMap::from([
                    ("bar".to_owned(), vec![None]),
                    ("baz".to_owned(), vec![None])
                ]),
            })]
        );
        assert_eq!(
            read_rows(&b"foo\n\nbar\n"[..]).unwrap(),
            vec![
                Rowlike::Row(Row {
                    label: "foo".to_owned(),
                    entries: HashMap::new(),
                }),
                Rowlike::Row(Row {
                    label: "bar".to_owned(),
                    entries: HashMap::new(),
                })
            ]
        );
        assert_eq!(
            read_rows(&b"foo\n\n\nbar\n"[..]).unwrap(),
            vec![
                Rowlike::Row(Row {
                    label: "foo".to_owned(),
                    entries: HashMap::new(),
                }),
                Rowlike::Spacer,
                Rowlike::Row(Row {
                    label: "bar".to_owned(),
                    entries: HashMap::new(),
                })
            ]
        );
        assert_eq!(
            read_rows(&b"foo\n \nbar\n"[..]).unwrap(),
            vec![
                Rowlike::Row(Row {
                    label: "foo".to_owned(),
                    entries: HashMap::new(),
                }),
                Rowlike::Row(Row {
                    label: "bar".to_owned(),
                    entries: HashMap::new(),
                })
            ]
        );
        assert_eq!(
            read_rows(&b"foo  \n bar  \n"[..]).unwrap(),
            vec![Rowlike::Row(Row {
                label: "foo".to_owned(),
                entries: HashMap::from([("bar".to_owned(), vec![None])]),
            })]
        );

        let bad = read_rows(&b" foo"[..]);
        assert!(bad.is_err());
        assert!(format!("{bad:?}").contains("1: Entry with no header"));

        let bad2 = read_rows(&b"foo\n\n bar"[..]);
        assert!(bad2.is_err());
        assert!(format!("{bad2:?}").contains("3: Entry with no header"));
    }

    #[test]
    fn test_read_config() {
        assert_eq!(
            read_config(&b"!col_threshold 10"[..]).unwrap(),
            Config {
                column_threshold: 10
            }
        );

        let bad_num = read_config(&b"!col_threshold foo"[..]);
        assert!(bad_num.is_err());
        assert!(format!("{bad_num:?}").contains("Parse"));
    }

    #[test]
    fn test_column_counts() {
        assert_eq!(
            column_counts(&read_rows(&b"foo\n bar\n baz\n"[..]).unwrap()),
            vec![(1, String::from("bar")), (1, String::from("baz"))]
        );
        assert_eq!(
            column_counts(&read_rows(&b"foo\n bar\n baz\nquux\n baz"[..]).unwrap()),
            vec![(2, String::from("baz")), (1, String::from("bar"))]
        );
        assert_eq!(
            column_counts(&read_rows(&b"foo\n bar\n bar\n baz\n bar\nquux\n baz"[..]).unwrap()),
            vec![(2, String::from("baz")), (1, String::from("bar"))]
        );
        assert_eq!(
            column_counts(
                &read_rows(&b"foo\n bar: 1\n bar: 2\n baz\n bar\nquux\n baz"[..]).unwrap()
            ),
            vec![(2, String::from("baz")), (1, String::from("bar"))]
        );
    }

    #[test]
    fn test_render_cell() {
        assert_eq!(
            render_cell(
                "foo",
                &mut Row {
                    label: "nope".to_owned(),
                    entries: HashMap::new(),
                }
            ),
            HTML::from(
                r#"<td class="" onmouseover="h2('nope','foo')" onmouseout="ch2('nope','foo')"></td>"#
            )
        );
        assert_eq!(
            render_cell(
                "foo",
                &mut Row {
                    label: "nope".to_owned(),
                    entries: HashMap::from([("bar".to_owned(), vec![None])]),
                }
            ),
            HTML::from(
                r#"<td class="" onmouseover="h2('nope','foo')" onmouseout="ch2('nope','foo')"></td>"#
            )
        );
        assert_eq!(
            render_cell(
                "foo",
                &mut Row {
                    label: "nope".to_owned(),
                    entries: HashMap::from([("foo".to_owned(), vec![None])]),
                }
            ),
            HTML::from(
                r#"<td class="yes" onmouseover="h2('nope','foo')" onmouseout="ch2('nope','foo')"></td>"#
            )
        );
        assert_eq!(
            render_cell(
                "foo",
                &mut Row {
                    label: "nope".to_owned(),
                    entries: HashMap::from([("foo".to_owned(), vec![None, None])]),
                }
            ),
            HTML::from(
                r#"<td class="yes" onmouseover="h2('nope','foo')" onmouseout="ch2('nope','foo')">2</td>"#
            )
        );
        assert_eq!(
            render_cell(
                "foo",
                &mut Row {
                    label: "nope".to_owned(),
                    entries: HashMap::from([(
                        "foo".to_owned(),
                        vec![Some("5".to_owned()), Some("10".to_owned())]
                    )]),
                }
            ),
            HTML::from(
                r#"<td class="yes" onmouseover="h2('nope','foo')" onmouseout="ch2('nope','foo')">5 10</td>"#
            )
        );
        assert_eq!(
            render_cell(
                "foo",
                &mut Row {
                    label: "nope".to_owned(),
                    entries: HashMap::from([("foo".to_owned(), vec![Some("5".to_owned()), None])]),
                }
            ),
            HTML::from(
                r#"<td class="yes" onmouseover="h2('nope','foo')" onmouseout="ch2('nope','foo')">5 ✓</td>"#
            )
        );
        assert_eq!(
            render_cell(
                "heart",
                &mut Row {
                    label: "nope".to_owned(),
                    entries: HashMap::from([("heart".to_owned(), vec![Some("<3".to_owned())])]),
                }
            ),
            HTML::from(
                r#"<td class="yes" onmouseover="h2('nope','heart')" onmouseout="ch2('nope','heart')">&lt;3</td>"#
            )
        );
        assert_eq!(
            render_cell(
                "foo",
                &mut Row {
                    label: "bob's".to_owned(),
                    entries: HashMap::from([("foo".to_owned(), vec![None])]),
                }
            ),
            HTML::from(
                r#"<td class="yes" onmouseover="h2('bob&#39;s','foo')" onmouseout="ch2('bob&#39;s','foo')"></td>"#
            )
        );
        let mut r = Row {
            label: "nope".to_owned(),
            entries: HashMap::from([
                ("foo".to_owned(), vec![None]),
                ("baz".to_owned(), vec![None]),
            ]),
        };
        assert_eq!(r.entries.len(), 2);
        render_cell("foo", &mut r);
        assert_eq!(r.entries.len(), 1);
        render_cell("bar", &mut r);
        assert_eq!(r.entries.len(), 1);
        render_cell("baz", &mut r);
        assert_eq!(r.entries.len(), 0);
    }

    #[test]
    fn test_render_leftovers() {
        assert_eq!(
            render_all_leftovers(&Row {
                label: "nope".to_owned(),
                entries: HashMap::from([("foo".to_owned(), vec![None])]),
            }),
            HTML::from("foo")
        );
        assert_eq!(
            render_all_leftovers(&Row {
                label: "nope".to_owned(),
                entries: HashMap::from([
                    ("foo".to_owned(), vec![None]),
                    ("bar".to_owned(), vec![None])
                ]),
            }),
            HTML::from("bar, foo")
        );
        assert_eq!(
            render_all_leftovers(&Row {
                label: "nope".to_owned(),
                entries: HashMap::from([
                    ("foo".to_owned(), vec![None]),
                    ("bar".to_owned(), vec![None, None])
                ]),
            }),
            HTML::from("bar: 2, foo")
        );
    }

    #[test]
    fn test_render_row() {
        assert_eq!(
            render_row(
                &["foo".to_owned()],
                &mut Rowlike::Row(Row {
                    label: "nope".to_owned(),
                    entries: HashMap::from([("bar".to_owned(), vec![None])]),
                })
            ),
            HTML::from(
                r#"<tr><th id="nope">nope</th><td class="" onmouseover="h2('nope','foo')" onmouseout="ch2('nope','foo')"></td><td class="leftover" onmouseover="highlight('nope')" onmouseout="clear_highlight('nope')">bar</td></tr>
"#
            )
        );
    }
}