#!/bin/bash

# Main author: Matthieu Moy <git@matthieu-moy.fr>
# (See the Git history for other contributors)
#
# BSD 2-Clause License
# 
# Copyright (c) 2012 - 2020, Matthieu Moy
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 
# 1. Redistributions of source code must retain the above copyright notice, this
#    list of conditions and the following disclaimer.
# 
# 2. Redistributions in binary form must reproduce the above copyright notice,
#    this list of conditions and the following disclaimer in the documentation
#    and/or other materials provided with the distribution.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# git-latexdiff is a wrapper around latexdiff
# (http://www.ctan.org/pkg/latexdiff) that allows using it to diff two
# revisions of a LaTeX file.
#
# The script internally checks out the full tree for the specified
# revisions, calls latexpand to flatten the document and then calls
# latexdiff-so (if available, otherwise latexdiff). Therefore,
# this works if the document is split into multiple .tex files.
#
# Try "git latexdiff -h" for more information.
#
# To install, just copy git-latexdiff in your $PATH.

# Missing features (patches welcome ;-):
# - diff the index
# - hardlink temporary checkouts as much as possible

# Alternatives:
#
# There is another script doing essentially the same here:
# https://github.com/cawka/latexdiff/blob/master/latexdiff-git
# My experience is that latexdiff-git is more buggy than
# git-latexdiff, but they probably just don't have the same bugs ;-)
#
# There are a bunch of other alternatives cited here:
#
#   http://tex.stackexchange.com/questions/1325/using-latexdiff-with-git
#
# Ideally, these scripts should be merged.

set -o errexit
set -o pipefail
set -o noclobber
# Used when symlinking files from the working tree: symlink .* files
# too.
shopt -s dotglob

# Some versions of git set $GIT_WORK_TREE when ran through an alias.
# This wouldn't work with git-latexdiff which plays with different
# work trees.
unset GIT_DIR
unset GIT_WORK_TREE

# (Comment and 'unset' line borrowed from Git's source code)
# Having this variable in your environment would break scripts because
# you would cause "cd" to be taken to unexpected places.  If you
# like CDPATH, define it for your interactive shell sessions without
# exporting it.
# But we protect ourselves from such a user mistake nevertheless.
unset CDPATH

# 1.6.0 is substituted by the install script here,
# but not within git_latexdiff_compute_version().
git_latexdiff_version='1.6.0'

git_latexdiff_compute_version () {
    if [ "$git_latexdiff_version" = '@GIT_LATEXDIFF''_VERSION@' ]; then
	(cd "$(dirname "$0")" && git describe --tags HEAD 2>/dev/null || echo 'Unknown version')
    else
	echo "$git_latexdiff_version"
    fi
}

usage () {
    cat << EOF
Usage: $(basename "$0" | sed 's/git-/git /') [options] OLD [NEW]
       $(basename "$0" | sed 's/git-/git /') [options] OLD --
       $(basename "$0" | sed 's/git-/git /') [options] -- OLD
Call latexdiff on two Git revisions of a file.

OLD and NEW are Git revision identifiers. NEW defaults to HEAD.
If "--" is used for NEW, then diff against the working directory.

Options:
    --help                this help message
    --help-examples       show examples of usage
    --main <file>         name of the main LaTeX, R Sweave,
                            or Emacs Org mode file.
                            The search for the only file containing 'documentclass'
                            will be attempted, if not specified.
                            For non-LaTeX files, a reasonable \`prepare\` command
                            will be used unless explicitly provided
    --no-view             don't display the resulting PDF file
    --latex               run latex instead of pdflatex
    --xelatex             run xelatex instead of pdflatex
    --lualatex            run lualatex instead of pdflatex
    --tectonic            run tectonic instead of pdflatex
    --bibtex, --bbl       display changes in the bibliography
                             (runs bibtex to generate *.bbl files and
                             include them in the source file using
                             latexpand --expand-bbl before computing
                             the diff)
    --biber               like --bibtex, but runs biber instead.
    --run-bibtex, -b      run bibtex as well as latex to generate the PDF file
                             (pdflatex,bibtex,pdflatex,pdflatex)
                          NOTE: --bibtex usually works better
    --run-biber           run BibLaTex-Biber as well as latex to generate the PDF file
                             (pdflatex,biber,pdflatex,pdflatex)
                          NOTE: --biber usually works better
    --view                view the resulting PDF file
                            (default if -o is not used)
    --pdf-viewer <cmd>    use <cmd> to view the PDF file (default: \$PDFVIEWER)
    --no-cleanup          don't cleanup temp dir after running
    --no-flatten          don't call latexpand to flatten the document
    --cleanup MODE        Cleanup temporary files according to MODE:

                           - keeppdf (default): keep only the
                                  generated PDF file

                           - none: keep all temporary files
                                  (may eat your diskspace)

                           - all: erase all generated files.
                                  Problematic with --view when the
                                  viewer is e.g. evince, and doesn't
                                  like when the file being viewed is
                                  deleted.

    --latexmk             use latexmk
    --build-dir           use pdfs from specific build directory
    --latexopt            pass additional options to latex (e.g. -shell-escape)
    -o <file>, --output <file>
                          copy resulting PDF into <file> (usually ending with .pdf)
                          Implies "--cleanup all"
    --tmpdirprefix        where temporary directory will be created (default: /tmp).
                            Relative path will use repository root as a base
    --verbose, -v         give more verbose output
    --quiet               redirect output from subprocesses to log files
    --prepare <cmd>       run <cmd> before latexdiff (e.g. run make to generate
                             included files)
    --filter <cmd>        run <cmd> after latexdiff and before compilation
                             (e.g. to fix up latexdiff output)
    --ln-untracked        symlink uncommited files from the working directory
    --version             show git-latexdiff version.
    --subtree             checkout the tree at and below the main file
                             (enabled by default, disable with --whole-tree)
    --whole-tree          checkout the whole tree (contrast with --subtree)
    --ignore-latex-errors keep on going even if latex gives errors, so long as
                          a PDF file is produced
    --ignore-makefile     ignore the Makefile, build as though it doesn't exist
    -*                    other options are passed directly to latexdiff
    --latexpand OPT       pass option OPT to latexpand. Use multiple times like
                          --latexpand OPT1 --latexpand OPT2 to pass multiple options.
    --latexdiff-flatten   use --flatten from latexdiff instead of latexpand

Unrecognized options are passed unmodified to latexdiff.
EOF
}

examples () {
    cat <<EOF
Examples:

Diff the previous revision with the latest commit:

    git latexdiff HEAD^

Diff the latest commit with the working tree:

    git latexdiff HEAD --

Diff latest commit with branch master:

    git latexdiff master HEAD

Pass --type=CHANGEBAR to latexdiff to get changebars in the margins
instead of red+trike/blue+underline diff:

    git latexdiff --type=CHANGEBAR HEAD^

Use a specific latexdiff configuration file:

    git latexdiff --config /path/to/file HEAD^
EOF
}

die () {
    echo "fatal: $*"
    exit 1
}

verbose () {
    if test "$verbose" = 1 ; then
	printf "%s ..." "$@"
    fi
}

verbose_progress () {
    if test "$verbose" = 1 ; then
	printf "."
    fi
}

verbose_done () {
    if test "$verbose" = 1 ; then
	echo " ${1:-done}."
    fi
}

verbose_say () {
    if test "$verbose" = 1 ; then
	printf "%s\n" "$@"
    fi
}

old=
new=
main=
view=maybe
cleanup=keeppdf
verbose=0
bibtex=0
biber=0
output=
initial_dir=$PWD
tmpdir_prefix="/tmp"
prepare_cmd=
flatten=1
subtree=1
uselatexmk=
use_build_dir=
latexopt=
ln_untracked=0
quiet=0
ignorelatexerrors=0
latexdiffopt=()
latexpand=()
bbl=0
latexdiff_flatten=0
latex=0
xelatex=0
lualatex=0
tectonic=0
BIBTEX_EXEC=bibtex

while test $# -ne 0; do
    case "$1" in
        "--help"|"-h")
            usage
            exit 0
            ;;
	"--help-examples")
	    examples
	    exit 0
	    ;;
	"--main")
	    test $# -gt 1 && shift || die "missing argument for $1"
	    main=$1
	    ;;
	"--no-view")
	    view=0
	    ;;
	"--view")
	    view=1
	    ;;
	"--pdf-viewer")
	    test $# -gt 1 && shift || die "missing argument for $1"
	    PDFVIEWER="$1"
	    ;;
	"--no-cleanup")
	    cleanup=none
	    ;;
	"--ignore-latex-errors")
	    ignorelatexerrors=1
	    ;;
        "--cleanup")
            shift
            case "$1" in
                "none"|"all"|"keeppdf")
                    cleanup="$1"
                    ;;
                *)
                    echo "Bad argument --cleanup $1"
                    usage
                    exit 1
                    ;;
            esac
            ;;
	"--no-flatten")
            flatten=0
            ;;
	"--ignore-makefile")
	    ignoremake=1
	    ;;
	"-o"|"--output")
	    test $# -gt 1 && shift || die "missing argument for $1"
	    output=$1
	    cleanup=all
	    ;;
	"-b"|"--bibtex")
	    bbl=1
	    ;;
	"--latex")
	    latex=1
	    ;;
	"--xelatex")
            xelatex=1
            ;;
	"--lualatex")
	    lualatex=1
	    ;;
	"--tectonic")
	    tectonic=1
	    ;;
	"--biber")
	    BIBTEX_EXEC=biber
	    bbl=1
	    ;;
	"--run-bibtex")
	    bibtex=1
	    ;;
	"--run-biber")
	    biber=1
	    ;;	
	"--verbose"|"-v")
	    verbose=1
	    ;;
        "--quiet")
	    quiet=1
	    ;;
	"--version")
	    git_latexdiff_compute_version
            exit 0
	    ;;
	"--subtree")
	    subtree=1
	    ;;
	"--whole-tree")
	    subtree=0
	    ;;
	"--prepare")
	    shift
	    prepare_cmd="$1"
	    ;;
	"--filter")
	    shift
	    filter_cmd="$1"
	    ;;
        "--build-dir")
	    test $# -gt 1 && shift || die "missing argument for $1"
	    use_build_dir=$1
            ;;
        "--latexmk")
            uselatexmk=1
            ;;
	"--latexpand")
	    shift
	    latexpand=("${latexpand[@]}" "$1")
	    ;;
	"--bbl")
	    bbl=1
	    ;;
	"--latexdiff-flatten")
	    latexdiff_flatten=1
            flatten=0
	    ;;
	"--latexopt")
	    shift
	    latexopt=$1
	    ;;
        "--ln-untracked")
            ln_untracked=1
            ;;
        "--no-ln-untracked")
            ln_untracked=0
            ;;
        "--tmpdirprefix")
	    shift
	    tmpdir_prefix="$1"
	    ;;
        -*)
            if test "$1" = "--" ; then
                if test -z "$new" ; then
                    new=$1
                else
                    echo "Bad argument $1"
                    usage
                    exit 1
                fi
            else
		case "$1" in
		    '--type'|'-t'|'--subtype'|'-s'|'--floattype'|'-f'|\
			'--config'|'-c'|'-p'|'--encoding'|'-e'|\
			'--label'|'-L'|'--exclude-safecmd'|'-A'|\
			'--replace-safecmd'|'--append-safecmd'|'-a'|\
			'--exclude-textcmd'|'-X'|'--replace-textcmd'|\
			'--append-textcmd'|'-x'|'--replace-context1cmd'|\
			'--append-context1cmd'|'--replace-context2cmd'|\
			'--append-context2cmd'|'--packages'|'--math-markup'|\
			'--driver')
			# Options taking an immediate argument in
			# latexdiff => add both the option and its
			# argument.
			latexdiffopt+=("$1" "$2")
			shift
			;;
		    '--preamble')
			# Same, but with a file argument. Make it
			# absolute to avoid issues when cd-ing
			# somewhere else.
			absolute="$(cd $(dirname "$2"); pwd)/$(basename "$2")"
			latexdiffopt+=("$1" "$absolute")
			shift
			;;
		    *)
			latexdiffopt+=("$1")
			;;
		esac
            fi
            ;;
        *)
	    if test -z "$1" ; then
		echo "Empty string not allowed as argument"
		usage
		exit 1
	    elif test -z "$old" ; then
		old=$1
	    elif test -z "$new" ; then
		new=$1
	    else
		echo "Bad argument $1"
		usage
		exit 1
	    fi
            ;;
    esac
    shift
done

initial_repo=$(git rev-parse --show-toplevel)

if test -z "$new" ; then
    new=HEAD
fi

if test -z "$old" ; then
    echo "fatal: Please, provide at least one revision to diff with."
    usage
    exit 1
fi

if test -z "$PDFVIEWER" ; then
    verbose "Auto-detecting PDF viewer"
    candidates="xdg-open evince okular xpdf acroread"
    if test "$(uname)" = Darwin ; then
        # open exists on GNU/Linux, but does not open PDFs
	candidates="open $candidates"
    fi

    for command in $candidates; do
	if command -v "$command" >/dev/null 2>&1; then
	    PDFVIEWER="$command"
	    break
	else
	    verbose_progress
	fi
    done
    verbose_done "$PDFVIEWER"
fi

case "$view" in
    maybe|1)
	if test -z "$PDFVIEWER" ; then
	    echo "warning: could not find a PDF viewer on your system."
	    echo "warning: Please set \$PDFVIEWER or use --pdf-viewer CMD."
	    PDFVIEWER=false
	fi
	;;
esac

if test $flatten = 1 &&
    ! command -v latexpand 2>/dev/null; then
    echo "Warning: latexpand not found. Falling back to latexdiff --flatten."
    latexdiff_flatten=1
    flatten=0
fi

if test $latex = 1; then
    LATEX_EXEC=latex
elif test $xelatex = 1; then
    LATEX_EXEC=xelatex
elif test $lualatex = 1; then
    LATEX_EXEC=lualatex
elif test $tectonic = 1; then
    LATEX_EXEC=tectonic
else
    LATEX_EXEC=pdflatex
fi

if test $biber = 1; then
    BIBTEX_EXEC=biber
fi

## end option parsing ##

check_knitr () {
    if test -z "$prepare_cmd"; then
	prepare_cmd="Rscript -e \"library(knitr); knit('$main')\""
    fi
    main="${main%\.*}.tex"
}

check_org () {
    if test -z "$prepare_cmd"; then
        prepare_cmd="emacs --batch --eval \"(load \\\"~/.emacs\\\")\" \"$main\" -f org-latex-export-to-latex --kill"
    fi
    main="${main%\.*}.tex"
}

log_cmd () {
    log=$1
    shift
    if [ "$quiet" = 1 ]; then
	"$@" >$log 2>&1
    else
	"$@"
    fi
}

# main is relative to initial_dir (if returned)
if test -z "$main" ; then
    printf "%s" "No --main provided, trying to guess ... "
    main=$(git grep -l '^[ \t]*\\documentclass')
    # May return multiple results, but if so the result won't be a file.
    if test -r "$main" ; then
	echo "Using $main as the main file."
    else
	if test -z "$main" ; then
	    echo "No candidate for main file."
	else
	    echo "Multiple candidates for main file:"
	    printf "%s\n" "$main" | sed 's/^/\t/'
	fi
	die "Please, provide a main file with --main FILE.tex."
    fi
fi

if test ! -r "$main" ; then
    die "Cannot read $main."
fi

ext=${main##*\.}
case "$ext" in
    Rnw) check_knitr ;;
    Rtex) check_knitr ;;
    org) check_org ;;
    *) ;;
esac

# Set LATEXDIFF_EXEC to either latexdiff or latexdiff-so. Prefer
# latexdiff-so if available.
if command -v latexdiff-so >/dev/null 2>&1; then
    LATEXDIFF_EXEC=latexdiff-so
elif command -v latexdiff >/dev/null 2>&1; then
    LATEXDIFF_EXEC=latexdiff
else
    die "latexdiff-so and latexdiff couldn't be found. Check your PATH."
fi
verbose_done "$LATEXDIFF_EXEC"

verbose "Creating temporary directories"

git_prefix=$(git rev-parse --show-prefix)
git_dir="$(git rev-parse --git-dir)" || die "Not a git repository?"
cd "$(git rev-parse --show-cdup)" || die "Can't cd back to repository root"
git_dir=$(cd "$git_dir"; pwd)
git_worktree=$(pwd)

relative_main_dir=$(dirname "$main")
# make main relative to git root directory
if test -n "$git_prefix" ; then
    main=$git_prefix$main
fi
mainbase=$(basename "$main" .tex)
maindir=$(dirname "$main")

tmpdir=$tmpdir_prefix/git-latexdiff.$$
mkdir "$tmpdir" || die "Cannot create temporary directory."

cd "$tmpdir" || die "Cannot cd to $tmpdir"
if test "$(uname -o 2>/dev/null)" = "Msys"; then
    tmpdir=$(pwd -W)
else
    tmpdir=$(pwd)
fi

mkdir old new || die "Cannot create old and new directories."

verbose_done
verbose_say "Temporary directories: $tmpdir/old and $tmpdir/new"
verbose "Checking out old and new version"

cd old || die "Cannot cd to old/"
if test "$ln_untracked" = 1; then
    (
	mkdir -p "$maindir" && cd "$maindir" &&
	    log_cmd ln-old.log ln -s "$initial_repo"/"$maindir"/* .
    ) || true
fi

if test "$subtree" = 1 && test -n "$git_prefix"; then
    checkoutroot=$git_prefix
else
    checkoutroot="."
fi
# create the build directory (containing the final PDFs) if the param was set
if test -n "$use_build_dir" ; then
    builddir="$use_build_dir"
else
    builddir="$relative_main_dir"
fi

# Checkout a subtree, without touching the index ("git checkout" would)
(cd "$git_dir" && git archive --format=tar "$old" "$checkoutroot") | tar -xf -
# Also expand the possible submodules
(cd "$git_worktree" && git submodule foreach --recursive 'git archive --format=tar "$sha1" | tar -xf - --directory '$tmpdir/old'/$displaypath')
verbose_progress
cd ../new || die "Cannot cd to new/"
if test "$new" == "--"; then
    # Copy working tree files
    (cd "$git_worktree" && git ls-files -- "$checkoutroot" | tar -cf - -T -) | tar -xf -
else
    # checkout new revision
    (cd "$git_dir" && git archive --format=tar "$new" "$checkoutroot") | tar -xf -
    (cd "$git_worktree" && git submodule foreach --recursive 'git archive --format=tar "$sha1" | tar -xf - --directory '$tmpdir/new'/$displaypath')
fi
if test "$ln_untracked" = 1; then
    (
	mkdir -p "$maindir" && cd "$maindir" &&
	    log_cmd ln-new.log ln -s "$initial_repo"/"$maindir"/* .
    ) || true
fi

verbose_progress
cd ..

verbose_done

for dir in old new
do
    verbose "Running preparation command $prepare_cmd in $dir/$git_prefix"
    ( cd "$dir/$git_prefix/" && log_cmd prepare.log eval "$prepare_cmd" )
    if test ! -f "$dir/$main"; then
	die "$prepare_cmd did not produce $dir/$main."
    fi
    verbose_done
done

if test $tectonic != 1; then
  if [ "$ignorelatexerrors" = 1 ]; then
      latexopt="$latexopt -interaction=batchmode"
  elif [ "$quiet" = 1 ]; then
      latexopt="$latexopt -interaction=nonstopmode"
  else
      latexopt="$latexopt -interaction=errorstopmode"
  fi
fi

# Option to use latexdiff --flatten instead of latexpand
if test "$latexdiff_flatten" = 1; then
    latexdiffopt+=("--flatten")
fi

# Shortcut to include bbl
if test "$bbl" = 1; then
    if test "$biber" = 1; then
	bblexpand=("--expand-bbl" "$mainbase.bbl")
	# In theory, this (with recent enough latexpand) should work
	# better. In practice it doesn't seem to work though.
	# bblexpand=("--biber" "$mainbase.bbl")
    else
	bblexpand=("--expand-bbl" "$mainbase.bbl")
    fi
else
    bblexpand=()
fi

ignore_errors_maybe() {
    if [ "$compile_error" = 1 ] && [ "$ignorelatexerrors" = 1 ]; then
	echo "LaTeX errors were found - but attempting to carry on."
	compile_error=0
    fi
}

# Create flattened documents and keep for debugging
if test "$flatten" = 1; then
    if [ "$bbl" = 1 ]; then
	if [ ! -f "old/$maindir$mainbase.bbl" ]; then
	    verbose "Attempting to regenerate missing old/$maindir$mainbase.bbl"
	    oldPWD=$PWD
	    cd old/"$maindir"
	    log_cmd pdflatex0.log $LATEX_EXEC $latexopt "$mainbase" || {
		compile_error=1
		error_msg="command 'pdflatex' (automatically run in old due to --bbl) failed."
	    }
	    log_cmd "$BIBTEX_EXEC"0.log $BIBTEX_EXEC "$mainbase" || {
		compile_error=1
		error_msg="command '$BIBTEX_EXEC' (automatically run in old due to --bbl) failed."
	    }
	    cd "$oldPWD"
	    ignore_errors_maybe
	    if [ "$compile_error" = 1 ]; then
		die "Failed to regenerate .bbl for old version"
	    fi
	fi
	if [ ! -f "new/$maindir$mainbase.bbl" ]; then
	    verbose "Attempting to regenerate missing new/$maindir$mainbase.bbl"
	    oldPWD=$PWD
	    cd new/"$maindir"
	    log_cmd pdflatex0.log $LATEX_EXEC $latexopt "$mainbase" || {
		compile_error=1
		error_msg="command 'pdflatex' (automatically run in new due to --bbl) failed."
	    }
	    log_cmd "$BIBTEX_EXEC"0.log $BIBTEX_EXEC "$mainbase" || {
		compile_error=1
		error_msg="command '$BIBTEX_EXEC' (automatically run in new due to --bbl) failed."
	    }
	    cd "$oldPWD"
	    ignore_errors_maybe
	    if [ "$compile_error" = 1 ]; then
		die "Failed to regenerate .bbl for new version"
	    fi
	fi
    fi
    verbose "Running latexpand"
    (
	cd old/"$maindir" &&
	latexpand "$mainbase".tex "${latexpand[@]}" "${bblexpand[@]}"
    ) > old-"$mainbase"-fl.tex \
	|| die "latexpand failed for old version"
    (
	cd new/"$maindir" &&
	latexpand "$mainbase".tex "${latexpand[@]}" "${bblexpand[@]}"
    ) > new-"$mainbase"-fl.tex \
	|| die "latexpand failed for new version"
    verbose_done

    verbose "Running $LATEXDIFF_EXEC ${latexdiffopt[*]} old-${mainbase}-fl.tex new-${mainbase}-fl.tex > ./diff.tex"
    "$LATEXDIFF_EXEC" "${latexdiffopt[@]}" old-"$mainbase"-fl.tex new-"$mainbase"-fl.tex > diff.tex \
	|| die "$LATEXDIFF_EXEC failed"
    verbose_done

    verbose "mv ./diff.tex new/$main"
    mv -f new/"$main" new/"$main".orig
    mv -f diff.tex new/"$main"
    verbose_done
else
    verbose "Running $LATEXDIFF_EXEC ${latexdiffopt[*]} old/$main new/$main > ./diff.tex"
    "$LATEXDIFF_EXEC" "${latexdiffopt[@]}" old/"$main" new/"$main" > diff.tex \
	|| die "$LATEXDIFF_EXEC failed"
    verbose_done

    verbose "mv ./diff.tex new/$main"
    mv -f new/"$main" new/"$main.orig"
    mv -f diff.tex new/"$main"
    verbose_done
fi

if [ ! -z "$filter_cmd" ]; then
    verbose "Running filter command $filter_cmd in new/"
    ( cd "new/" && log_cmd filter.log eval "$filter_cmd" )
    if [ ! -f "new/$main" ]; then
	die "$filter_cmd removed new/$main."
    fi
    verbose_done
fi

verbose "Compiling result"

compile_error=0

oldPWD=$PWD
cd new/"$maindir" || die "Can't cd to new/$maindir"
if test -f Makefile && test "$ignoremake" != 1 ; then
    log_cmd make.log make || {
	compile_error=1
	error_msg="command 'make' failed."
    }
elif test "$uselatexmk" = 1; then
    log_cmd latexmk.log latexmk -f -pdf -silent $latexopt "$mainbase" || {
	compile_error=1
	error_msg="command 'latexmk' failed."
    }
elif test "$tectonic" = 1; then
    log_cmd tectonic.log tectonic $latexopt "$mainbase.tex" || {
	compile_error=1
	error_msg="command 'tectonic' failed."
    }
else
    log_cmd pdflatex1.log $LATEX_EXEC $latexopt "$mainbase" || {
	compile_error=1
	error_msg="command pdflatex (first run) failed."
    }
    if test "$bibtex" = 1 || test "$biber" = 1 ; then
	log_cmd "$BIBTEX_EXEC".log $BIBTEX_EXEC "$mainbase" || {
	    compile_error=1
	    error_msg="command '$BIBTEX_EXEC' failed."
	}
    fi
    log_cmd pdflatex2.log $LATEX_EXEC $latexopt "$mainbase" || {
	compile_error=1
	error_msg="command 'pdflatex' (second run) failed."
    }
    log_cmd pdflatex3.log $LATEX_EXEC $latexopt "$mainbase" || {
	compile_error=1
	error_msg="command 'pdflatex' (third run) failed."
    }
fi
cd "$oldPWD"

# Same relative path as where we've been called from, but in the
# temporary new/ directory:
cd new/"$git_prefix"

verbose_done

ignore_errors_maybe

if test $latex = 1; then
    dvips "$mainbase".dvi
    ps2pdf "$mainbase".ps
fi

pdffile="$builddir/$mainbase".pdf
if test ! -r "$pdffile" ; then
    echo "No PDF file generated."
    echo "Working directory: $PWD"
    echo "Expected PDF: $pdffile"
    compile_error=1
elif test ! -s "$pdffile" ; then
    echo "PDF file generated is empty."
    compile_error=1
fi

if test "$compile_error" = "1" ; then
    echo "Error during compilation. Please examine and cleanup if needed:"
    echo "Directory: $tmpdir/new/$maindir"
    echo "     File: $mainbase.tex"
    echo "  Problem: $error_msg"
    # Don't clean up to let the user diagnose.
    exit 1
fi

if test -n "$output" ; then
    abs_pdffile="$PWD/$pdffile"
    (cd "$initial_dir" && mv "$abs_pdffile" "$output")
    pdffile="$output"
    echo "Output written on $pdffile"
elif [ -f "$pdffile" ]; then
    new_pdffile="$tmpdir"/"$mainbase".pdf
    mv "$pdffile" "$new_pdffile"
    pdffile="$new_pdffile"
fi

# Change directory so nothing will keep us from cleaning
cd "$initial_dir"

if test "$view" = 1 || ( test "$view" = maybe  && test -z "$output" ) ; then
    "$PDFVIEWER" "$pdffile"
fi

case "$cleanup" in
    "all")
	verbose "Cleaning-up result"
	rm -fr "$tmpdir"
	verbose_done
	;;
    "keeppdf")
	verbose "Cleaning-up all but pdf (kept in $pdffile)"
	rm -fr "$tmpdir"/old "$tmpdir"/new
	verbose_done
	;;
    "none")
	verbose_say "Generated files kept in $tmpdir/"
	;;
esac