{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE OverloadedStrings #-}

-- |
-- Module      : $header$
-- Description : Pandoc filter to create figures from code blocks using your plotting toolkit of choice
-- Copyright   : (c) Laurent P René de Cotret, 2020
-- License     : GNU GPL, version 2 or above
-- Maintainer  : laurent.decotret@outlook.com
-- Stability   : unstable
-- Portability : portable
--
-- This module defines a Pandoc filter @plotTransform@ and related functions
-- that can be used to walk over a Pandoc document and generate figures from
-- code blocks, using a multitude of plotting toolkits.
--
-- The syntax for code blocks is simple. Code blocks with the appropriate class
-- attribute will trigger the filter:
--
-- *   @matplotlib@ for matplotlib-based Python plots;
-- *   @plotly_python@ for Plotly-based Python plots;
-- *   @plotly_r@ for Plotly-based R plots;
-- *   @matlabplot@ for MATLAB plots;
-- *   @mathplot@ for Mathematica plots;
-- *   @octaveplot@ for GNU Octave plots;
-- *   @ggplot2@ for ggplot2-based R plots;
-- *   @gnuplot@ for gnuplot plots;
-- *   @graphviz@ for Graphviz graphs;
-- *   @bokeh@ for Bokeh-based Python plots;
-- *   @plotsjl@ for Plots.jl-based Julia plots;
--
-- For example, in Markdown:
--
-- @
--     This is a paragraph.
--
--     ```{.matlabplot}
--     figure()
--     plot([1,2,3,4,5], [1,2,3,4,5], '-k')
--     ```
-- @
--
-- The code block will be reworked into a script and the output figure will be captured. Optionally, the source code
--  used to generate the figure will be linked in the caption.
--
-- Here are the possible attributes what pandoc-plot understands for ALL toolkits:
--
--     * @directory=...@ : Directory where to save the figure. This path should be specified with
--       respect to the current working directory, and not with respect to the document.
--     * @source=true|false@ : Whether or not to link the source code of this figure in the caption.
--       Ideal for web pages, for example. Default is false.
--     * @format=...@: Format of the generated figure. This can be an extension or an acronym,
--       e.g. @format=PNG@.
--     * @caption="..."@: Specify a plot caption (or alternate text). Format
--       for captions is specified in the documentation for the @Configuration@ type.
--     * @dpi=...@: Specify a value for figure resolution, or dots-per-inch. Certain toolkits ignore this.
--     * @dependencies=[...]@: Specify files/directories on which a figure depends, e.g. data file.
--       Figures will be re-rendered if one of those file/directory changes. These paths should
--       be specified with respect to the current working directory, and not with respect to the document.
--     * @preamble=...@: Path to a file to include before the code block. Ideal to avoid repetition over
--       many figures.
--     * @file=...@: Path to a file from which to read the content of the figure. The content of the
--       code block will be ignored. This path should be specified with respect to the current working
--       directory, and not with respect to the document.
--
-- Default values for the above attributes are stored in the @Configuration@ datatype. These can be specified in a
-- YAML file.
--
-- Here is an example code block which will render a figure using gnuplot, in Markdown:
--
-- @
--     ```{.gnuplot format=png caption="Sinusoidal function" source=true}
--     sin(x)
--
--     set xlabel "x"
--     set ylabel "y"
--     ```
-- @
module Text.Pandoc.Filter.Plot
  ( -- * Operating on whole Pandoc documents
    plotTransform,

    -- * Cleaning output directories
    cleanOutputDirs,

    -- * Runtime configuration
    configuration,
    defaultConfiguration,
    Configuration (..),
    Verbosity (..),
    LogSink (..),
    SaveFormat (..),
    Script,

    -- * Determining available plotting toolkits
    Toolkit (..),
    availableToolkits,
    unavailableToolkits,
    toolkits,
    supportedSaveFormats,

    -- * Version information
    pandocPlotVersion,

    -- * For embedding, testing and internal purposes ONLY. Might change without notice.
    make,
    makeEither,
    PandocPlotError (..),
  )
where

import Control.Concurrent.Async.Lifted (mapConcurrently)
import Data.Text (Text, unpack)
import Data.Version (Version)
import Paths_pandoc_plot (version)
import Text.Pandoc.Definition (Block, Pandoc (..))
import Text.Pandoc.Filter.Plot.Internal
  ( Configuration (..),
    FigureSpec,
    LogSink (..),
    PlotM,
    RuntimeEnv (envConfig),
    SaveFormat (..),
    Script,
    ScriptResult (..),
    Toolkit (..),
    Verbosity (..),
    asks,
    availableToolkits,
    cleanOutputDirs,
    configuration,
    defaultConfiguration,
    parseFigureSpec,
    runPlotM,
    runScriptIfNecessary,
    supportedSaveFormats,
    toFigure,
    toolkits,
    unavailableToolkits,
  )

-- | Walk over an entire Pandoc document, transforming appropriate code blocks
-- into figures. This function will operate on blocks in parallel if possible.
--
-- Failing to render a figure does not stop the filter, so that you may run the filter
-- on documents without having all necessary toolkits installed. In this case, error
-- messages are printed to stderr, and blocks are left unchanged.
plotTransform ::
  -- | Configuration for default values
  Configuration ->
  -- | Input document
  Pandoc ->
  IO Pandoc
plotTransform conf (Pandoc meta blocks) =
  runPlotM conf $ mapConcurrently make blocks >>= return . Pandoc meta

-- | The version of the pandoc-plot package.
--
-- @since 0.8.0.0
pandocPlotVersion :: Version
pandocPlotVersion = version

-- | Try to process the block with `pandoc-plot`. If a failure happens (or the block)
-- was not meant to become a figure, return the block as-is.
make :: Block -> PlotM Block
make blk = either (const (return blk)) return =<< makeEither blk

-- | Try to process the block with `pandoc-plot`, documenting the error.
makeEither :: Block -> PlotM (Either PandocPlotError Block)
makeEither block =
  parseFigureSpec block
    >>= maybe
      (return $ Right block)
      (\s -> runScriptIfNecessary s >>= handleResult s)
  where
    -- Logging of errors has been taken care of in @runScriptIfNecessary@
    handleResult :: FigureSpec -> ScriptResult -> PlotM (Either PandocPlotError Block)
    handleResult _ (ScriptFailure msg code) = return $ Left (ScriptRuntimeError msg code)
    handleResult _ (ScriptChecksFailed msg) = return $ Left (ScriptChecksFailedError msg)
    handleResult _ (ToolkitNotInstalled tk') = return $ Left (ToolkitNotInstalledError tk')
    handleResult spec ScriptSuccess = asks envConfig >>= \c -> Right <$> toFigure (captionFormat c) spec

data PandocPlotError
  = ScriptRuntimeError Text Int
  | ScriptChecksFailedError Text
  | ToolkitNotInstalledError Toolkit

instance Show PandocPlotError where
  show (ScriptRuntimeError _ exitcode) = "ERROR (pandoc-plot) The script failed with exit code " <> show exitcode <> "."
  show (ScriptChecksFailedError msg) = "ERROR (pandoc-plot) A script check failed with message: " <> unpack msg <> "."
  show (ToolkitNotInstalledError tk) = "ERROR (pandoc-plot) The " <> show tk <> " toolkit is required but not installed."