// Copyright 2017-2020 the Tectonic Project
// Licensed under the MIT License.

#![deny(missing_docs)]

//! A framework for showing status messages to the user.
//!
//! A lot of the functionality here could be replaced by generic logging
//! frameworks, but we do have some extra hooks to help support a nice user
//! experience for the Tectonic CLI tool.

use std::{cmp::Ordering, fmt::Arguments, result::Result as StdResult, str::FromStr};
use tectonic_errors::Error;

pub mod plain;

/// A kind of status message.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum MessageKind {
    /// An informational notice.
    Note,

    /// A message about a condition that's unexpected or undesirable, but not a
    /// showstopper.
    Warning,

    /// A message about a condition that is going to prevent the program from
    /// doing what the user intended.
    Error,
}

/// A setting regarding which messages to display.
#[repr(usize)]
#[non_exhaustive]
#[derive(Clone, Copy, Debug, Default, Eq)]
pub enum ChatterLevel {
    /// Suppress all informational output.
    Minimal = 0,

    /// Normal output levels.
    #[default]
    Normal,
}

impl ChatterLevel {
    /// Determine whether messages of the specified kind should be suppressed at
    /// this chatter level.
    pub fn suppress_message(&self, kind: MessageKind) -> bool {
        match self {
            ChatterLevel::Normal => false,
            ChatterLevel::Minimal => kind == MessageKind::Note,
        }
    }
}

impl FromStr for ChatterLevel {
    type Err = &'static str;

    fn from_str(a_str: &str) -> StdResult<Self, Self::Err> {
        match a_str {
            "default" => Ok(ChatterLevel::Normal),
            "minimal" => Ok(ChatterLevel::Minimal),
            _ => Err("unsupported or unknown chatter level"),
        }
    }
}

impl PartialEq for ChatterLevel {
    #[inline]
    fn eq(&self, other: &ChatterLevel) -> bool {
        *self as usize == *other as usize
    }
}

impl PartialOrd for ChatterLevel {
    #[inline]
    fn partial_cmp(&self, other: &ChatterLevel) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

impl Ord for ChatterLevel {
    #[inline]
    fn cmp(&self, other: &ChatterLevel) -> Ordering {
        (*self as usize).cmp(&(*other as usize))
    }
}

/// A trait for accepting status messages.
pub trait StatusBackend {
    /// Report a message to the status backend.
    ///
    /// If `err` is not None, it represents an error that somehow caused the
    /// current message to be reported. It should be displayed in some
    /// appropriate fashion.
    fn report(&mut self, kind: MessageKind, args: Arguments, err: Option<&Error>);

    /// Report an error to the status backend.
    ///
    /// Unlike the basic `report` function, in this case there is no additional
    /// contextual information provided. The default implementation delegates to
    /// `report()` with a generic lead-in message of "an error occurred".
    fn report_error(&mut self, err: &Error) {
        self.report(
            MessageKind::Error,
            format_args!("an error occurred"),
            Some(err),
        )
    }

    /// Issue a note-level status, idealy highlighting a particular phrase.
    ///
    /// This is a bit of a hack. I like the UX when we issue notes in this
    /// style. It's a bit more high-level than intended for this trait, but we
    /// can provide a nice sensible default implementation, so whatever.
    fn note_highlighted(&mut self, before: &str, highlighted: &str, after: &str) {
        self.report(
            MessageKind::Note,
            format_args!("{before}{highlighted}{after}"),
            None,
        )
    }

    /// This is used to print TeX engine logs after it encountered errors. This
    /// should print the provided output, which may span many lines, with some
    /// clear delineation.
    fn dump_error_logs(&mut self, output: &[u8]);
}

/// Report a formatted informational message to the user.
///
/// An `Error` object may be provided, in which case it will be shown to the
/// user as well. Generally, though, one would expect to use `tt_warning!` or
/// `tt_error!` if there’s an Error available.
#[macro_export]
macro_rules! tt_note {
    ($dest:expr, $( $fmt_args:expr ),*) => {
        $dest.report($crate::MessageKind::Note, format_args!($( $fmt_args ),*), None)
    };
    ($dest:expr, $( $fmt_args:expr ),* ; $err:expr) => {
        $dest.report($crate::MessageKind::Note, format_args!($( $fmt_args ),*), Some(&$err))
    };
}

/// Report a formatted warning message to the user.
///
/// An `Error` object may be provided, in which case it will be shown to the
/// user as well.
#[macro_export]
macro_rules! tt_warning {
    ($dest:expr, $( $fmt_args:expr ),*) => {
        $dest.report($crate::MessageKind::Warning, format_args!($( $fmt_args ),*), None)
    };
    ($dest:expr, $( $fmt_args:expr ),* ; $err:expr) => {
        $dest.report($crate::MessageKind::Warning, format_args!($( $fmt_args ),*), Some(&$err))
    };
}

/// Report a formatted error message to the user.
///
/// An `Error` object may be provided, in which case it will be shown to the
/// user as well.
#[macro_export]
macro_rules! tt_error {
    ($dest:expr, $( $fmt_args:expr ),*) => {
        $dest.report($crate::MessageKind::Error, format_args!($( $fmt_args ),*), None)
    };
    ($dest:expr, $( $fmt_args:expr ),* ; $err:expr) => {
        $dest.report($crate::MessageKind::Error, format_args!($( $fmt_args ),*), Some(&$err))
    };
}

/// A status backend that does nothing at all. Messages sent to it disappear
/// entirely.
#[derive(Copy, Clone, Debug, Default)]
pub struct NoopStatusBackend {}

impl StatusBackend for NoopStatusBackend {
    fn report(&mut self, _kind: MessageKind, _args: Arguments, _err: Option<&Error>) {}
    fn dump_error_logs(&mut self, _output: &[u8]) {}
}