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    //! Support for CLI progress bars.

    use std::cmp;
    use std::time::{Duration, Instant};

    use crate::core::shell::Verbosity;
    use crate::util::context::ProgressWhen;
    use crate::util::{CargoResult, GlobalContext};
    use cargo_util::is_ci;
    use unicode_width::UnicodeWidthChar;

    /// CLI progress bar.
    ///
    /// The `Progress` object can be in an enabled or disabled state. When
    /// disabled, calling any of the methods to update it will not display
    /// anything. Disabling is typically done by the user with options such as
    /// `--quiet` or the `term.progress` config option.
    ///
    /// There are several methods to update the progress bar and to cause it to
    /// update its display.
    ///
    /// The bar will be removed from the display when the `Progress` object is
    /// dropped or [`Progress::clear`] is called.
    ///
    /// The progress bar has built-in rate limiting to avoid updating the display
    /// too fast. It should usually be fine to call [`Progress::tick`] as often as
    /// needed, though be cautious if the tick rate is very high or it is
    /// expensive to compute the progress value.
    pub struct Progress<'gctx> {
        state: Option<State<'gctx>>,
    }

    /// Indicates the style of information for displaying the amount of progress.
    ///
    /// See also [`Progress::print_now`] for displaying progress without a bar.
    pub enum ProgressStyle {
        /// Displays progress as a percentage.
        ///
        /// Example: `Fetch [=====================>   ]  88.15%`
        ///
        /// This is good for large values like number of bytes downloaded.
        Percentage,
        /// Displays progress as a ratio.
        ///
        /// Example: `Building [===>                      ] 35/222`
        ///
        /// This is good for smaller values where the exact number is useful to see.
        Ratio,
        /// Does not display an exact value of how far along it is.
        ///
        /// Example: `Fetch [===========>                     ]`
        ///
        /// This is good for situations where the exact value is an approximation,
        /// and thus there isn't anything accurate to display to the user.
        Indeterminate,
    }

    struct Throttle {
        first: bool,
        last_update: Instant,
    }

    struct State<'gctx> {
        gctx: &'gctx GlobalContext,
        format: Format,
        name: String,
        done: bool,
        throttle: Throttle,
        last_line: Option<String>,
        fixed_width: Option<usize>,
    }

    struct Format {
        style: ProgressStyle,
        max_width: usize,
        max_print: usize,
    }

    impl<'gctx> Progress<'gctx> {
        /// Creates a new progress bar.
        ///
        /// The first parameter is the text displayed to the left of the bar, such
        /// as "Fetching".
        ///
        /// The progress bar is not displayed until explicitly updated with one if
        /// its methods.
        ///
        /// The progress bar may be created in a disabled state if the user has
        /// disabled progress display (such as with the `--quiet` option).
        pub fn with_style(
            name: &str,
            style: ProgressStyle,
            gctx: &'gctx GlobalContext,
        ) -> Progress<'gctx> {
            // report no progress when -q (for quiet) or TERM=dumb are set
            // or if running on Continuous Integration service like Travis where the
            // output logs get mangled.
            let dumb = match gctx.get_env("TERM") {
                Ok(term) => term == "dumb",
                Err(_) => false,
            };
            let progress_config = gctx.progress_config();
            match progress_config.when {
                ProgressWhen::Always => return Progress::new_priv(name, style, gctx),
                ProgressWhen::Never => return Progress { state: None },
                ProgressWhen::Auto => {}
            }
            if gctx.shell().verbosity() == Verbosity::Quiet || dumb || is_ci() {
                return Progress { state: None };
            }
            Progress::new_priv(name, style, gctx)
        }

        fn new_priv(name: &str, style: ProgressStyle, gctx: &'gctx GlobalContext) -> Progress<'gctx> {
            let progress_config = gctx.progress_config();
            let width = progress_config
                .width
                .or_else(|| gctx.shell().err_width().progress_max_width());

            Progress {
                state: width.map(|n| State {
                    gctx,
                    format: Format {
                        style,
                        max_width: n,
                        // 50 gives some space for text after the progress bar,
                        // even on narrow (e.g. 80 char) terminals.
                        max_print: 50,
                    },
                    name: name.to_string(),
                    done: false,
                    throttle: Throttle::new(),
                    last_line: None,
                    fixed_width: progress_config.width,
                }),
            }
        }

        /// Disables the progress bar, ensuring it won't be displayed.
        pub fn disable(&mut self) {
            self.state = None;
        }

        /// Returns whether or not the progress bar is allowed to be displayed.
        pub fn is_enabled(&self) -> bool {
            self.state.is_some()
        }

        /// Creates a new `Progress` with the [`ProgressStyle::Percentage`] style.
        ///
        /// See [`Progress::with_style`] for more information.
        pub fn new(name: &str, gctx: &'gctx GlobalContext) -> Progress<'gctx> {
            Self::with_style(name, ProgressStyle::Percentage, gctx)
        }

        /// Updates the state of the progress bar.
        ///
        /// * `cur` should be how far along the progress is.
        /// * `max` is the maximum value for the progress bar.
        /// * `msg` is a small piece of text to display at the end of the progress
        ///   bar. It will be truncated with `...` if it does not fit on the
        ///   terminal.
        ///
        /// This may not actually update the display if `tick` is being called too
        /// quickly.
        pub fn tick(&mut self, cur: usize, max: usize, msg: &str) -> CargoResult<()> {
            let Some(s) = &mut self.state else {
                return Ok(());
            };

            // Don't update too often as it can cause excessive performance loss
            // just putting stuff onto the terminal. We also want to avoid
            // flickering by not drawing anything that goes away too quickly. As a
            // result we've got two branches here:
            //
            // 1. If we haven't drawn anything, we wait for a period of time to
            //    actually start drawing to the console. This ensures that
            //    short-lived operations don't flicker on the console. Currently
            //    there's a 500ms delay to when we first draw something.
            // 2. If we've drawn something, then we rate limit ourselves to only
            //    draw to the console every so often. Currently there's a 100ms
            //    delay between updates.
            if !s.throttle.allowed() {
                return Ok(());
            }

            s.tick(cur, max, msg)
        }

        /// Updates the state of the progress bar.
        ///
        /// This is the same as [`Progress::tick`], but ignores rate throttling
        /// and forces the display to be updated immediately.
        ///
        /// This may be useful for situations where you know you aren't calling
        /// `tick` too fast, and accurate information is more important than
        /// limiting the console update rate.
        pub fn tick_now(&mut self, cur: usize, max: usize, msg: &str) -> CargoResult<()> {
            match self.state {
                Some(ref mut s) => s.tick(cur, max, msg),
                None => Ok(()),
            }
        }

        /// Returns whether or not updates are currently being throttled.
        ///
        /// This can be useful if computing the values for calling the
        /// [`Progress::tick`] function may require some expensive work.
        pub fn update_allowed(&mut self) -> bool {
            match &mut self.state {
                Some(s) => s.throttle.allowed(),
                None => false,
            }
        }

        /// Displays progress without a bar.
        ///
        /// The given `msg` is the text to display after the status message.
        ///
        /// Example: `Downloading 61 crates, remaining bytes: 28.0 MB`
        ///
        /// This does not have any rate limit throttling, so be careful about
        /// calling it too often.
        pub fn print_now(&mut self, msg: &str) -> CargoResult<()> {
            match &mut self.state {
                Some(s) => s.print("", msg),
                None => Ok(()),
            }
        }

        /// Clears the progress bar from the console.
        pub fn clear(&mut self) {
            if let Some(ref mut s) = self.state {
                s.clear();
            }
        }
    }

    impl Throttle {
        fn new() -> Throttle {
            Throttle {
                first: true,
                last_update: Instant::now(),
            }
        }

        fn allowed(&mut self) -> bool {
            if self.first {
                let delay = Duration::from_millis(500);
                if self.last_update.elapsed() < delay {
                    return false;
                }
            } else {
                let interval = Duration::from_millis(100);
                if self.last_update.elapsed() < interval {
                    return false;
                }
            }
            self.update();
            true
        }

        fn update(&mut self) {
            self.first = false;
            self.last_update = Instant::now();
        }
    }

    impl<'gctx> State<'gctx> {
        fn tick(&mut self, cur: usize, max: usize, msg: &str) -> CargoResult<()> {
            if self.done {
                return Ok(());
            }

            if max > 0 && cur == max {
                self.done = true;
            }

            // Write out a pretty header, then the progress bar itself, and then
            // return back to the beginning of the line for the next print.
            self.try_update_max_width();
            if let Some(pbar) = self.format.progress(cur, max) {
                self.print(&pbar, msg)?;
            }
            Ok(())
        }

        fn print(&mut self, prefix: &str, msg: &str) -> CargoResult<()> {
            self.throttle.update();
            self.try_update_max_width();

            // make sure we have enough room for the header
            if self.format.max_width < 15 {
                return Ok(());
            }

            let mut line = prefix.to_string();
            self.format.render(&mut line, msg);
            while line.len() < self.format.max_width - 15 {
                line.push(' ');
            }

            // Only update if the line has changed.
            if self.gctx.shell().is_cleared() || self.last_line.as_ref() != Some(&line) {
                let mut shell = self.gctx.shell();
                shell.set_needs_clear(false);
                shell.status_header(&self.name)?;
                write!(shell.err(), "{}\r", line)?;
                self.last_line = Some(line);
                shell.set_needs_clear(true);
            }

            Ok(())
        }

        fn clear(&mut self) {
            // No need to clear if the progress is not currently being displayed.
            if self.last_line.is_some() && !self.gctx.shell().is_cleared() {
                self.gctx.shell().err_erase_line();
                self.last_line = None;
            }
        }

        fn try_update_max_width(&mut self) {
            if self.fixed_width.is_none() {
                if let Some(n) = self.gctx.shell().err_width().progress_max_width() {
                    self.format.max_width = n;
                }
            }
        }
    }

    impl Format {
        fn progress(&self, cur: usize, max: usize) -> Option<String> {
            assert!(cur <= max);
            // Render the percentage at the far right and then figure how long the
            // progress bar is
            let pct = (cur as f64) / (max as f64);
            let pct = if !pct.is_finite() { 0.0 } else { pct };
            let stats = match self.style {
                ProgressStyle::Percentage => format!(" {:6.02}%", pct * 100.0),
                ProgressStyle::Ratio => format!(" {}/{}", cur, max),
                ProgressStyle::Indeterminate => String::new(),
            };
            let extra_len = stats.len() + 2 /* [ and ] */ + 15 /* status header */;
            let Some(display_width) = self.width().checked_sub(extra_len) else {
                return None;
            };

            let mut string = String::with_capacity(self.max_width);
            string.push('[');
            let hashes = display_width as f64 * pct;
            let hashes = hashes as usize;

            // Draw the `===>`
            if hashes > 0 {
                for _ in 0..hashes - 1 {
                    string.push('=');
                }
                if cur == max {
                    string.push('=');
                } else {
                    string.push('>');
                }
            }

            // Draw the empty space we have left to do
            for _ in 0..(display_width - hashes) {
                string.push(' ');
            }
            string.push(']');
            string.push_str(&stats);

            Some(string)
        }

        fn render(&self, string: &mut String, msg: &str) {
            let mut avail_msg_len = self.max_width - string.len() - 15;
            let mut ellipsis_pos = 0;
            if avail_msg_len <= 3 {
                return;
            }
            for c in msg.chars() {
                let display_width = c.width().unwrap_or(0);
                if avail_msg_len >= display_width {
                    avail_msg_len -= display_width;
                    string.push(c);
                    if avail_msg_len >= 3 {
                        ellipsis_pos = string.len();
                    }
                } else {
                    string.truncate(ellipsis_pos);
                    string.push_str("...");
                    break;
                }
            }
        }

        #[cfg(test)]
        fn progress_status(&self, cur: usize, max: usize, msg: &str) -> Option<String> {
            let mut ret = self.progress(cur, max)?;
            self.render(&mut ret, msg);
            Some(ret)
        }

        fn width(&self) -> usize {
            cmp::min(self.max_width, self.max_print)
        }
    }

    impl<'gctx> Drop for State<'gctx> {
        fn drop(&mut self) {
            self.clear();
        }
    }

    #[test]
    fn test_progress_status() {
        let format = Format {
            style: ProgressStyle::Ratio,
            max_print: 40,
            max_width: 60,
        };
        assert_eq!(
            format.progress_status(0, 4, ""),
            Some("[                   ] 0/4".to_string())
        );
        assert_eq!(
            format.progress_status(1, 4, ""),
            Some("[===>               ] 1/4".to_string())
        );
        assert_eq!(
            format.progress_status(2, 4, ""),
            Some("[========>          ] 2/4".to_string())
        );
        assert_eq!(
            format.progress_status(3, 4, ""),
            Some("[=============>     ] 3/4".to_string())
        );
        assert_eq!(
            format.progress_status(4, 4, ""),
            Some("[===================] 4/4".to_string())
        );

        assert_eq!(
            format.progress_status(3999, 4000, ""),
            Some("[===========> ] 3999/4000".to_string())
        );
        assert_eq!(
            format.progress_status(4000, 4000, ""),
            Some("[=============] 4000/4000".to_string())
        );

        assert_eq!(
            format.progress_status(3, 4, ": short message"),
            Some("[=============>     ] 3/4: short message".to_string())
        );
        assert_eq!(
            format.progress_status(3, 4, ": msg thats just fit"),
            Some("[=============>     ] 3/4: msg thats just fit".to_string())
        );
        assert_eq!(
            format.progress_status(3, 4, ": msg that's just fit"),
            Some("[=============>     ] 3/4: msg that's just...".to_string())
        );

        // combining diacritics have width zero and thus can fit max_width.
        let zalgo_msg = "z̸̧̢̗͉̝̦͍̱ͧͦͨ̑̅̌ͥ́͢a̢ͬͨ̽ͯ̅̑ͥ͋̏̑ͫ̄͢͏̫̝̪̤͎̱̣͍̭̞̙̱͙͍̘̭͚l̶̡̛̥̝̰̭̹̯̯̞̪͇̱̦͙͔̘̼͇͓̈ͨ͗ͧ̓͒ͦ̀̇ͣ̈ͭ͊͛̃̑͒̿̕͜g̸̷̢̩̻̻͚̠͓̞̥͐ͩ͌̑ͥ̊̽͋͐̐͌͛̐̇̑ͨ́ͅo͙̳̣͔̰̠̜͕͕̞̦̙̭̜̯̹̬̻̓͑ͦ͋̈̉͌̃ͯ̀̂͠ͅ ̸̡͎̦̲̖̤̺̜̮̱̰̥͔̯̅̏ͬ̂ͨ̋̃̽̈́̾̔̇ͣ̚͜͜h̡ͫ̐̅̿̍̀͜҉̛͇̭̹̰̠͙̞ẽ̶̙̹̳̖͉͎̦͂̋̓ͮ̔ͬ̐̀͂̌͑̒͆̚͜͠ ͓͓̟͍̮̬̝̝̰͓͎̼̻ͦ͐̾̔͒̃̓͟͟c̮̦͍̺͈͚̯͕̄̒͐̂͊̊͗͊ͤͣ̀͘̕͝͞o̶͍͚͍̣̮͌ͦ̽̑ͩ̅ͮ̐̽̏͗́͂̅ͪ͠m̷̧͖̻͔̥̪̭͉͉̤̻͖̩̤͖̘ͦ̂͌̆̂ͦ̒͊ͯͬ͊̉̌ͬ͝͡e̵̹̣͍̜̺̤̤̯̫̹̠̮͎͙̯͚̰̼͗͐̀̒͂̉̀̚͝͞s̵̲͍͙͖̪͓͓̺̱̭̩̣͖̣ͤͤ͂̎̈͗͆ͨͪ̆̈͗͝͠";
        assert_eq!(
            format.progress_status(3, 4, zalgo_msg),
            Some("[=============>     ] 3/4".to_string() + zalgo_msg)
        );

        // some non-ASCII ellipsize test
        assert_eq!(
            format.progress_status(3, 4, "_123456789123456e\u{301}\u{301}8\u{301}90a"),
            Some("[=============>     ] 3/4_123456789123456e\u{301}\u{301}...".to_string())
        );
        assert_eq!(
            format.progress_status(3, 4, "：每個漢字佔據了兩個字元"),
            Some("[=============>     ] 3/4：每個漢字佔據了...".to_string())
        );
        assert_eq!(
            // handle breaking at middle of character
            format.progress_status(3, 4, "：-每個漢字佔據了兩個字元"),
            Some("[=============>     ] 3/4：-每個漢字佔據了...".to_string())
        );
    }

    #[test]
    fn test_progress_status_percentage() {
        let format = Format {
            style: ProgressStyle::Percentage,
            max_print: 40,
            max_width: 60,
        };
        assert_eq!(
            format.progress_status(0, 77, ""),
            Some("[               ]   0.00%".to_string())
        );
        assert_eq!(
            format.progress_status(1, 77, ""),
            Some("[               ]   1.30%".to_string())
        );
        assert_eq!(
            format.progress_status(76, 77, ""),
            Some("[=============> ]  98.70%".to_string())
        );
        assert_eq!(
            format.progress_status(77, 77, ""),
            Some("[===============] 100.00%".to_string())
        );
    }

    #[test]
    fn test_progress_status_too_short() {
        let format = Format {
            style: ProgressStyle::Percentage,
            max_print: 25,
            max_width: 25,
        };
        assert_eq!(
            format.progress_status(1, 1, ""),
            Some("[] 100.00%".to_string())
        );

        let format = Format {
            style: ProgressStyle::Percentage,
            max_print: 24,
            max_width: 24,
        };
        assert_eq!(format.progress_status(1, 1, ""), None);
    }