//! Terminal presentation: colour, emphasis, and a live spinner while a
//! command works. Everything degrades to plain text when stdout is not a
//! terminal, when `NO_COLOR` is set, or with `--plain`.

use console::{style, StyledObject, Term};
use indicatif::{ProgressBar, ProgressStyle};
use std::sync::atomic::{AtomicBool, Ordering};
use std::time::Duration;

static PLAIN: AtomicBool = AtomicBool::new(false);
static UNICODE: AtomicBool = AtomicBool::new(false);
static INIT: std::sync::Once = std::sync::Once::new();

/// Decide once whether to use colour, glyphs, and animation.
pub fn init(plain_flag: bool) {
    INIT.call_once(|| {
        let no_color = std::env::var_os("NO_COLOR").is_some();
        let tty = Term::stdout().features().is_attended();
        let plain = plain_flag || no_color || !tty;
        PLAIN.store(plain, Ordering::Relaxed);
        console::set_colors_enabled(!plain);
        let utf8 = ["LC_ALL", "LC_CTYPE", "LANG"]
            .iter()
            .filter_map(|k| std::env::var(k).ok())
            .find(|v| !v.is_empty())
            .map(|v| {
                v.to_ascii_uppercase().contains("UTF-8") || v.to_ascii_uppercase().contains("UTF8")
            })
            .unwrap_or(false);
        UNICODE.store(!plain && utf8, Ordering::Relaxed);
    });
}

pub fn plain() -> bool {
    PLAIN.load(Ordering::Relaxed)
}

/// Whether the terminal takes Unicode glyphs (a UTF-8 locale, not `--plain`).
pub fn unicode() -> bool {
    UNICODE.load(Ordering::Relaxed)
}

/// A glyph with an ASCII fallback for plain output and non-UTF-8 locales.
pub fn glyph<'a>(fancy: &'a str, ascii: &'a str) -> &'a str {
    if unicode() {
        fancy
    } else {
        ascii
    }
}

/// A finished action: a tick and the verb in green.
pub fn done<T: std::fmt::Display>(v: T) -> String {
    format!("{} {}", ok(glyph("✔", "*")), ok(v))
}

/// A warning line prefix.
pub fn caution() -> String {
    warn(glyph("⚠", "!"))
}

/// An informational note prefix.
pub fn note() -> String {
    dim(glyph("ℹ", "i"))
}

/// A section title.
pub fn section<T: std::fmt::Display>(v: T) -> String {
    format!("{} {}", s(glyph("▍", "#")).cyan(), s(v).bold())
}

/// `  key   value`, with the key dimmed and padded.
pub fn kv<T: std::fmt::Display>(key: &str, value: T) -> String {
    format!("  {} {value}", dim(format!("{key:<8}")))
}

/// An author name.
pub fn author<T: std::fmt::Display>(v: T) -> String {
    s(v).magenta().to_string()
}

/// A bookmark or reference name.
pub fn bookmark<T: std::fmt::Display>(v: T) -> String {
    s(v).green().bold().to_string()
}

/// The subject line of a message.
pub fn subject<T: std::fmt::Display>(v: T) -> String {
    s(v).bold().to_string()
}

/// A dimmed separator between the parts of a metadata line.
pub fn sep() -> String {
    dim(format!(" {} ", glyph("·", "-")))
}

/// Milliseconds since the epoch as a relative time ("3 minutes ago"), or the
/// date when older than a month.
pub fn ago(ms: u64) -> String {
    let now = std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH)
        .map(|d| d.as_millis() as u64)
        .unwrap_or(0);
    let secs = now.saturating_sub(ms) / 1000;
    let unit = |n: u64, w: &str| format!("{n} {w}{} ago", if n == 1 { "" } else { "s" });
    match secs {
        0..=44 => "just now".into(),
        45..=89 => "a minute ago".into(),
        90..=2_699 => unit(secs.div_ceil(60), "minute"),
        2_700..=5_399 => "an hour ago".into(),
        5_400..=79_199 => unit(secs.div_ceil(3_600), "hour"),
        79_200..=129_599 => "yesterday".into(),
        129_600..=2_591_999 => unit(secs.div_ceil(86_400), "day"),
        _ => super::format::when(ms)
            .split(' ')
            .next()
            .unwrap_or("")
            .to_string(),
    }
}

/// The bullet for a log entry: the working copy, a head, or an ordinary change.
pub fn log_bullet(working_copy: bool, head: bool, conflicted: bool) -> String {
    if working_copy {
        s(glyph("◉", "@")).cyan().bold().to_string()
    } else if conflicted {
        err(glyph("✱", "!"))
    } else if head {
        ok(glyph("●", "*"))
    } else {
        dim(glyph("○", "o"))
    }
}

/// A status glyph and word for a working-copy change.
pub fn status_mark(tag: &str) -> String {
    let (g, a, word) = match tag {
        "A" => ("✚", "+", "added"),
        "M" => ("✎", "~", "modified"),
        "D" => ("✖", "-", "removed"),
        "X" => ("⚙", "x", "mode"),
        "C!" => ("‼", "!", "markers"),
        "R" => ("➜", ">", "renamed"),
        "V" => ("✔", "r", "resolved"),
        _ => ("?", "?", "unknown"),
    };
    let text = format!("{} {word:<9}", glyph(g, a));
    self::tag_style(tag, &text)
}

fn tag_style(t: &str, text: &str) -> String {
    match t {
        "A" | "V" => s(text).green().to_string(),
        "R" => s(text).cyan().to_string(),
        "M" | "X" => s(text).yellow().to_string(),
        "D" | "C!" => s(text).red().to_string(),
        _ => text.to_string(),
    }
}

fn s<T: std::fmt::Display>(v: T) -> StyledObject<T> {
    style(v)
}

/// A ChangeId prefix.
pub fn id<T: std::fmt::Display>(v: T) -> String {
    s(v).cyan().bold().to_string()
}
/// A hash prefix.
pub fn hash<T: std::fmt::Display>(v: T) -> String {
    s(v).dim().to_string()
}
pub fn path<T: std::fmt::Display>(v: T) -> String {
    s(v).bold().to_string()
}
pub fn ok<T: std::fmt::Display>(v: T) -> String {
    s(v).green().to_string()
}
pub fn warn<T: std::fmt::Display>(v: T) -> String {
    s(v).yellow().to_string()
}
pub fn err<T: std::fmt::Display>(v: T) -> String {
    s(v).red().bold().to_string()
}
pub fn dim<T: std::fmt::Display>(v: T) -> String {
    s(v).dim().to_string()
}
pub fn heading<T: std::fmt::Display>(v: T) -> String {
    s(v).bold().underlined().to_string()
}
/// A live spinner with a message, shown only on a terminal. Drop or call
/// `done` to clear it; `done` prints the final line in its place.
pub struct Spinner {
    bar: Option<ProgressBar>,
}

pub fn spinner(msg: &str) -> Spinner {
    if plain() {
        return Spinner { bar: None };
    }
    let bar = ProgressBar::new_spinner();
    bar.set_style(
        ProgressStyle::with_template("{spinner:.cyan} {msg}")
            .unwrap()
            .tick_strings(&["⠋", "⠙", "⠹", "⠸", "⠼", "⠴", "⠦", "⠧", "⠇", "⠏", "✔"]),
    );
    bar.set_message(msg.to_string());
    bar.enable_steady_tick(Duration::from_millis(80));
    Spinner { bar: Some(bar) }
}

impl Spinner {
    /// Replace the spinner with a final line (or print it plainly).
    pub fn done(self, msg: &str) {
        match &self.bar {
            Some(b) => b.finish_with_message(msg.to_string()),
            None => println!("{msg}"),
        }
    }
    /// Clear the spinner without printing.
    pub fn clear(self) {
        if let Some(b) = &self.bar {
            b.finish_and_clear();
        }
    }
}

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

    #[test]
    fn relative_times() {
        let now = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .unwrap()
            .as_millis() as u64;
        assert_eq!(ago(now), "just now");
        assert_eq!(ago(now - 60_000), "a minute ago");
        assert_eq!(ago(now - 5 * 60_000), "5 minutes ago");
        assert_eq!(ago(now - 3 * 3_600_000), "3 hours ago");
        assert_eq!(ago(now - 25 * 3_600_000), "yesterday");
        assert_eq!(ago(now - 4 * 86_400_000), "4 days ago");
        assert_eq!(ago(0), "1970-01-01");
        assert_eq!(glyph("✔", "*"), if unicode() { "✔" } else { "*" });
    }
}