#!/usr/bin/env python

import sys
import importlib
import os
import shutil
import platform

# Nuclex SCons libraries
sys.path.append('../../References/scripts/scons')
nuclex = importlib.import_module('nuclex')
archive = importlib.import_module('archive')

# ----------------------------------------------------------------------------------------------- #

universal_ilmbase_target_name = 'ilmbase'

environment = nuclex.create_cplusplus_environment()

# ----------------------------------------------------------------------------------------------- #
# Step 0: preparatory work

# Fetch the list of headers used when compiling
ilmbase_headers_file = environment.File('ilmbase-headers')
ilmbase_header_files = archive.split_lines(ilmbase_headers_file.get_text_contents())

# Fetch the list of sources to compile ilmbase
ilmbase_sources_file = environment.File('ilmbase-sources')
ilmbase_source_files = archive.split_lines(ilmbase_sources_file.get_text_contents())

# ----------------------------------------------------------------------------------------------- #
# Step 1: Download the current release

# Fetch the available download URLs from a file
download_url_file = environment.File('ilmbase-download-urls')
download_urls = archive.split_lines(download_url_file.get_text_contents())

# Determine the target filename for the download (below 'downloads' folder)
archive_filename = os.path.basename(download_urls[0])
archive_file = environment.File(os.path.join('downloads', archive_filename))

# Tell SCons how to "produce" the downloaded archive (by calling wget)
if not archive_file.exists():
    download_archive = environment.Command(
        source = download_url_file,
        #action = 'wget ' + download_urls[0] + ' --output-document=$TARGET',
        action = archive.download_url_in_urlfile,
        target = archive_file
    )

# ----------------------------------------------------------------------------------------------- #
# Step 2: Extract the release into the build directory

def extract_compressed_tarball(target, source, env):
    """Extracts the distribution .tar.gz archive and applies a patch that ensures
    the same headers will work on Windows and average Linux distributions.

    @param  target  Output files, not used by the function but passed along so
                    SCons can look at them and knows its dependency tree
    @param  source  Source files, expected to be an array containing the .tar.gz
                    path and the unified diff path
    @param  env     SCons build environment"""

    archive.extract_compressed_tarball(str(source[0]), 'build', 1)

    # SCons is too stupid to be told to copy the frigging file AFTER
    # extraction, so we'll work around the sucker:
    shutil.copyfile(
        'IlmBaseConfig.h',
        'build/config/IlmBaseConfig.h'
    )

ilmbase_header_files.append('build/config/IlmBaseConfig.h')

if platform.system() == 'Windows':
    ilmbase_source_files.append('build/IlmThread/IlmThreadMutexWin32.cpp')
    ilmbase_source_files.append('build/IlmThread/IlmThreadSemaphoreWin32.cpp')
    ilmbase_source_files.append('build/IlmThread/IlmThreadWin32.cpp')
else:
    ilmbase_source_files.append('build/IlmThread/IlmThreadMutexPosix.cpp')
    ilmbase_source_files.append('build/IlmThread/IlmThreadSemaphorePosix.cpp')
    ilmbase_source_files.append('build/IlmThread/IlmThreadPosix.cpp')

# Tell SCons how to "produce" the sources & headers (by calling tar)
extract_archive = environment.Command(
    source = archive_file,
    #action = 'tar --extract --gzip --strip-components=1 --file=$SOURCE --directory=build',
    action = extract_compressed_tarball,
    target = (
        ilmbase_source_files + ilmbase_header_files +
        [ 'build/Half/eLut.cpp', 'build/Half/toFloat.cpp' ]
    )
)

# Note: eLut.cpp and toFloat.cpp are part of the archive, but shouldn't be
# compiled to ilmbase.lib / libilmbase.a. That's why they're not in
# ilmbase_source_files.

# ----------------------------------------------------------------------------------------------- #
# Step 3: Compile and run the eLut look-up-table generator

elut_environment = environment.Clone()
del elut_environment['SOURCE_DIRECTORY'] # We define the sources ourselves
del elut_environment['HEADER_DIRECTORY'] # The generator has no internal header dependencies

# Add eLut.cpp as the single source file we're going to compile
elut_environment.add_source_directory(
    'build/Half',
    [ 'build/Half/eLut.cpp' ],
    scons_issue_2908_workaround_needed = True
)

# Build the eLut executable
compile_elut = elut_environment.build_executable(
    'eLut', console = True
)

# Run the code generator to generate the eLut.h header
elut_header = elut_environment.Command(
    source = compile_elut,
    action = '$SOURCE > $TARGET',
    target = 'build/Half/eLut.h'
)

# Add the generated header to ilmbase_header_files so it gets copied into
# the 'Include' directory with the other headers
ilmbase_header_files.append('build/Half/eLut.h')

# ERROR: These make SCons invent a circular dependency from eLut.cpp to eLut.h ?!
#elut_environment.Depends('build/Half/half.cpp', 'build/Half/eLut.h')
#elut_environment.Depends('build/Half/half.cpp', elut_header)

# ----------------------------------------------------------------------------------------------- #
# Step 4: Compile and run the toFloat look-up-table generator

tofloat_environment = environment.Clone()
del tofloat_environment['SOURCE_DIRECTORY'] # We define the sources ourselves
del tofloat_environment['HEADER_DIRECTORY'] # The generator has no internal header dependencies

# Add toFloat.cpp as the single source file we're going to compile
tofloat_environment.add_source_directory(
    'build/Half',
    [ 'build/Half/toFloat.cpp' ],
    scons_issue_2908_workaround_needed = True
)

# Build the toFloat executable
compile_tofloat = tofloat_environment.build_executable(
    'toFloat', console = True
)

# Run the code generator to generate the toFloat.h header
tofloat_header = tofloat_environment.Command(
    source = compile_tofloat,
    action = '$SOURCE > $TARGET',
    target = 'build/Half/toFloat.h'
)

# Add the generated header to ilmbase_header_files so it gets copied into
# the 'Include' directory with the other headers
ilmbase_header_files.append('build/Half/toFloat.h')

# ERROR: These make SCons invent a circular dependency from toFloat.cpp to toFloat.h ?!
#tofloat_environment.Depends('build/Half/half.cpp', 'build/Half/toFloat.h')
#tofloat_environment.Depends('build/Half/half.cpp', tofloat_header)

# ----------------------------------------------------------------------------------------------- #
# Step 5: Compile the ilmbase library

ilmbase_environment = environment.Clone()

del ilmbase_environment['SOURCE_DIRECTORY'] # We define the sources ourselves
ilmbase_environment['HEADER_DIRECTORY'] = 'build/config' # Main include directory

# Set up additional include directories for the 3 ilmbase modules
ilmbase_environment.add_include_directory('build/Iex')
ilmbase_environment.add_include_directory('build/IexMath')
ilmbase_environment.add_include_directory('build/Half')

# Add all sources from the sources list to this build
ilmbase_environment.add_source_directory(
    'build',
    ilmbase_source_files,
    scons_issue_2908_workaround_needed = True
)

# And finally, compile the ilmbase.lib / libilmbase.a library
compile_ilmbase_library = ilmbase_environment.build_library(
    universal_ilmbase_target_name,
    static = True
)

# ----------------------------------------------------------------------------------------------- #
# Step 6: Create an 'Include' directory containing only the headers

for header in ilmbase_header_files:
    if header.startswith('build/'):
        install_path = os.path.join('Include', header[6:])
        environment.InstallAs(install_path, header)

# ----------------------------------------------------------------------------------------------- #