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//! Generator generates final output for showing.

pub mod helper;
mod tag;

#[cfg(feature = "tui")]
pub mod tui;
#[cfg(feature = "tui")]
pub use self::tui::TuiTextGenerator;

use std::fmt::Display;

use crate::{error::LocatedError, parser::ItemG};

pub use tag::{Tag, TagConvertor, TagG};

/// Generator generates final output to show tui markup in some backend.
///
/// ## How to add support for new backend
///
/// Some concepts:
///
/// - Markup text/Source: the text you write in tui markup language.
/// - [Parser][crate::parser::parse]: parse markup text into a series of [Item][crate::parser::Item],
/// which usually be called as AST.
/// - [Tag Convertor][TagConvertor]: Convert raw tag string like `green`, `bg:66ccff`, `mod:b` into [Tag].
/// - [Generator]: generator final output from `Item<Tag>`.
///
/// So the whole pipeline is:
///
/// ```none
/// Source --- Parser --> Item --- Tag Convertor --> Item<Tag> --- Generator --> Output --> Show it in some backend
/// ```
///
/// The source, parser, Item, Tag, is already defined, so just write a [Tag Convertor][TagConvertor] and a [Generator], a new backend
/// will be supported.
pub trait Generator<'a>
where
    Self::Err: LocatedError + Display,
    Self::Convertor: TagConvertor<'a>,
{
    /// Tag convertor type.
    type Convertor;

    /// Output type.
    type Output;

    /// Error type.
    ///
    /// If the generator can't fall, please use [`GeneratorInfallible`][helper::GeneratorInfallible].
    type Err;

    /// Get the tag convertor.
    fn convertor(&mut self) -> &mut Self::Convertor;

    /// Generates final output from ast, which is output result of the Convertor.
    fn generate(&mut self, markup: Vec<Vec<ItemG<'a, Self>>>) -> Result<Self::Output, Self::Err>;
}

impl<'a, G: Generator<'a>> Generator<'a> for &mut G
where
    G::Err: LocatedError + Display,
    G::Convertor: TagConvertor<'a>,
{
    type Convertor = G::Convertor;

    type Output = G::Output;

    type Err = G::Err;

    fn convertor(&mut self) -> &mut Self::Convertor {
        <G as Generator<'a>>::convertor(self)
    }

    fn generate(&mut self, ir: Vec<Vec<ItemG<'a, G>>>) -> Result<Self::Output, Self::Err> {
        <G as Generator<'a>>::generate(self, ir)
    }
}