r3bl_tui 0.1.2

/*
 *   Copyright (c) 2022 R3BL LLC
 *   All rights reserved.
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *   limitations under the License.
 */

use std::{collections::{hash_map::Entry, HashMap},
          fmt::Debug,
          ops::{AddAssign, Deref, DerefMut}};

use serde::{Deserialize, Serialize};

use super::*;
use crate::{tui::DEBUG_SHOW_PIPELINE_EXPANDED, *};

// ┏━━━━━━━━━━━━━━━━━━┓
// ┃ render_pipeline! ┃
// ┛                  ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
/// This works w/ [RenderOp] items. It allows them to be added in sequence, and then flushed at the
/// end.
/// 1. This pipeline is meant to hold a list of [RenderOp] items.
/// 2. Once all the [RenderOp] items are added to the correct [ZOrder]s they can then be flushed at
///    the end in order to [paint](RenderPipeline::paint) them to the screen.
/// 3. All the paint operations mutate the global [cursor_position](TWData::cursor_position).
/// 4. The [RENDER_ORDERED_Z_ORDER_ARRAY] contains the priority that is used to paint the different
///    groups of [RenderOp] items.
///
/// This adds given [RenderOp]s to a [RenderOps] and adds that the the pipeline, but does not flush
/// anything. It will return a [RenderPipeline].
///
/// Here's an example.
///
/// ```rust
/// use r3bl_tui::*;
///
/// let mut pipeline = render_pipeline!(@new ZOrder::Normal =>
///   RenderOp::ClearScreen,
///   RenderOp::ResetColor
/// ); // Returns the newly created pipeline.
/// let len = pipeline.len();
/// let iter = pipeline.iter();
/// ```
///
/// Another example.
///
/// ```rust
/// use r3bl_tui::*;
///
/// let mut pipeline = render_pipeline!();
/// render_pipeline!(@push_into pipeline at ZOrder::Normal =>
///   RenderOp::ClearScreen,
///   RenderOp::ResetColor
/// ); // Returns nothing.
/// let len = pipeline.len();
/// let iter = pipeline.iter();
/// ```
///
/// Decl macro docs:
/// - <https://veykril.github.io/tlborm/decl-macros/macros-methodical.html#repetitions> HashMap
/// docs:
/// - <https://doc.rust-lang.org/std/collections/struct.HashMap.html#examples>
#[macro_export]
macro_rules! render_pipeline {
  // No args. Returns a new
  () => {
    RenderPipeline::default()
  };

  // @new: Create a new pipeline & return it. If any RenderOp ($arg_render_op)* are passed, then add it
  // to new pipeline.
  (
    @new
    $arg_z_order: expr
    => $(                   /* Start a repetition. */
      $arg_render_op: expr  /* Expression. */
    )                       /* End repetition. */
    ,                       /* Comma separated. */
    *                       /* Zero or more times. */
  ) => {
    /* Enclose the expansion in a block so that we can use multiple statements. */
    {
      let mut render_ops = RenderOps::default();
      /* Start a repetition. */
      $(
        /* Each repeat will contain the following statement, with $arg_render_op replaced. */
        render_ops.push($arg_render_op);
      )*
      let mut render_pipeline = RenderPipeline::default();
      render_pipeline.push($arg_z_order, render_ops);
      render_pipeline
    }
  };

  // @push_into: Add a bunch of RenderOp $arg_render_op+ to the existing $arg_pipeline & return nothing.
  (
    @push_into
    $arg_pipeline: ident
    at $arg_z_order: expr
    => $($arg_render_op: expr),+
  ) => {
    let mut render_ops = RenderOps::default();
    $(
      /* Each repeat will contain the following statement, with $arg_render_op replaced. */
      render_ops.push($arg_render_op);
    )*
    $arg_pipeline.push($arg_z_order, render_ops);
  };

  // @join_and_drop: Add $arg_other_pipeline+ (a bunch of other RenderPipelines) to the new
  // pipeline, drop them, and return it.
  (
    @join_and_drop
    $($arg_other_pipeline: expr),+
  ) => {{
    let mut pipeline = render_pipeline!();
    $(
      /* Each repeat will contain the following statement, with $arg_other_pipeline replaced. */
      pipeline.join_into($arg_other_pipeline);
    )*
    pipeline
  }};

  // @styled_text: Add a bunch of RenderOp $element+ to the existing $arg_pipeline, then render
  // $arg_styled_text into it.
  (
    @styled_text
    $arg_pipeline: ident
    at $arg_z_order: expr
    => $($element: expr),+
    => $arg_styled_text: ident
  ) => {
    let mut render_ops = RenderOps::default();
    $(
      /* Each repeat will contain the following statement, with $element replaced. */
      render_ops.push($element);
    )*
    $arg_styled_text.render_into(&mut render_ops);
    $arg_pipeline.push($arg_z_order, render_ops);
  };
}

// ┏━━━━━━━━━━━━━━━━┓
// ┃ RenderPipeline ┃
// ┛                ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
/// Here's an example. Consider using the macro for convenience (see [render_pipeline!]). Also see
/// [TWData] for more information on scoping the [cursor_position](TWData::cursor_position) rules.
///
/// ```rust
/// use r3bl_tui::*;
///
/// let mut pipeline = render_pipeline!();
/// pipeline.push(ZOrder::Normal, render_ops!(@new RenderOp::ClearScreen));
/// pipeline.push(ZOrder::Glass, render_ops!(@new RenderOp::CursorShow));
/// let len = pipeline.len();
/// let iter = pipeline.iter();
/// ```
#[derive(Default, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub struct RenderPipeline {
  /// [RenderOps] to paint for each [ZOrder].
  pub pipeline_map: PipelineMap,
}

type PipelineMap = HashMap<ZOrder, Vec<RenderOps>>;

impl RenderPipeline {
  /// This will add `rhs` to `self`.
  pub fn join_into(&mut self, mut rhs: RenderPipeline) {
    for (z_order, mut rhs_render_ops_vec) in rhs.drain() {
      // Insert rhs_render_ops_vec into self_render_ops_vec.
      match self.entry(z_order) {
        Entry::Occupied(mut self_existing_entry) => {
          let self_render_ops_vec = self_existing_entry.get_mut();
          rhs_render_ops_vec.drain(..).for_each(|render_ops| {
            self_render_ops_vec.push(render_ops);
          });
        }
        Entry::Vacant(self_new_entry) => {
          self_new_entry.insert(rhs_render_ops_vec);
        }
      }
    }
  }

  /// Add the given [RenderOps] to the pipeline at the given [ZOrder].
  pub fn push(&mut self, z_order: ZOrder, render_ops: RenderOps) {
    match self.pipeline_map.entry(z_order) {
      // Insert render_ops into existing set.
      Entry::Occupied(mut existing_entry) => {
        let render_ops_vec = existing_entry.get_mut();
        render_ops_vec.push(render_ops);
      }
      // Create new set & insert render_ops in it.
      Entry::Vacant(new_entry) => {
        new_entry.insert(vec![render_ops]);
      }
    }
  }

  /// At the given [ZOrder] there can be a [Vec] of [RenderOps]. Grab all the [RenderOps] in the
  /// set, get all their [RenderOp] and return them in a [Vec].
  pub fn get_all_render_op_in(&self, z_order: ZOrder) -> Option<Vec<RenderOp>> {
    let vec_render_ops = self.pipeline_map.get(&z_order)?;
    let mut vec_render_op: Vec<RenderOp> = vec![];
    for render_ops in vec_render_ops {
      for render_op in render_ops.iter() {
        vec_render_op.push(render_op.clone());
      }
    }
    Some(vec_render_op)
  }

  /// Some of the paint operations mutate the global [cursor_position](TWData::cursor_position).
  pub async fn paint(&self, flush_kind: FlushKind, shared_tw_data: &SharedTWData) {
    paint(self, flush_kind, shared_tw_data).await;
    // FUTURE: support termion, along w/ crossterm, by providing another impl of this fn #24
  }

  /// Move the [RenderOps] in the 'from' [ZOrder] (in self) to the 'to' [ZOrder] (in self).
  pub fn hoist(&mut self, z_order_from: ZOrder, z_order_to: ZOrder) {
    // If the 'from' [ZOrder] is not in the pipeline, then there's nothing to do.
    if !self.pipeline_map.contains_key(&z_order_from) {
      return;
    }

    // Move the [RenderOps] from the 'from' [ZOrder] to the 'to' [ZOrder].
    let mut from = self.pipeline_map.remove(&z_order_from).unwrap_or_default();

    match self.pipeline_map.entry(z_order_to) {
      Entry::Occupied(mut to_existing_entry) => {
        let to = to_existing_entry.get_mut();
        from.drain(..).for_each(|render_ops| {
          to.push(render_ops);
        });
      }
      Entry::Vacant(to_new_entry) => {
        to_new_entry.insert(from);
      }
    }
  }
}

pub mod z_order_impl {
  use super::*;

  /// Contains the priority that is used to paint the different groups of [RenderOp] items.
  pub const RENDER_ORDERED_Z_ORDER_ARRAY: [ZOrder; 3] = [ZOrder::Normal, ZOrder::High, ZOrder::Glass];

  #[derive(Debug, Copy, Clone, Serialize, Deserialize, PartialEq, Eq, Hash)]
  pub enum ZOrder {
    Normal,
    High,
    Glass,
  }

  impl Default for ZOrder {
    fn default() -> Self { Self::Normal }
  }
}
pub use z_order_impl::*;

mod render_pipeline_helpers {
  use super::*;

  impl Deref for RenderPipeline {
    type Target = PipelineMap;

    fn deref(&self) -> &Self::Target { &self.pipeline_map }
  }

  impl DerefMut for RenderPipeline {
    fn deref_mut(&mut self) -> &mut Self::Target { &mut self.pipeline_map }
  }

  impl Debug for RenderPipeline {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
      let mut vec_lines: Vec<String> = vec![];
      if DEBUG_SHOW_PIPELINE_EXPANDED {
        for (z_order, render_ops) in &**self {
          let line: String = format!("[{z_order:?}] {render_ops:?}");
          vec_lines.push(line);
        }
      } else {
        for (z_order, vec_render_ops) in &**self {
          let line: String = format!("[{z_order:?}] {:?} RenderOps", vec_render_ops.len());
          vec_lines.push(line);
        }
      }
      write!(f, "  - {}", vec_lines.join("\n  - "))
    }
  }

  impl AddAssign for RenderPipeline {
    fn add_assign(&mut self, other: RenderPipeline) { self.join_into(other); }
  }
}