# source: https://github.com/hgomersall/scons-jinja

# 2025-03-28: Added JINJA_GLOBALS options.
# 2023-12-02: Added JINJA_FILTERS option.

#
# Copyright (c) 2013 Henry Gomersall <heng@kedevelopments.co.uk>
# Copyright (c) 2025 Patrick Wuttke <mewin@mewin.de>
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#

import SCons.Builder
import SCons.Tool
from SCons.Errors import StopError

import jinja2
from jinja2 import FileSystemLoader
from jinja2.utils import open_if_exists
from jinja2.exceptions import TemplateNotFound

import os

class FileSystemLoaderRecorder(FileSystemLoader):
    ''' A wrapper around FileSystemLoader that records files as they are
    loaded. These are contained within loaded_filenames set attribute.
    '''
    def __init__(self, searchpath, encoding='utf-8'):

        self.loaded_filenames = set()
        super(FileSystemLoaderRecorder, self).__init__(searchpath, encoding)

    def get_source(self, environment, template):
        '''Overwritten FileSystemLoader.get_source method that extracts the
        filename that is used to load each filename and adds it to
        self.loaded_filenames.
        '''
        for searchpath in self.searchpath:
            filename = os.path.join(searchpath, template)
            f = open_if_exists(filename)
            if f is None:
                continue
            try:
                contents = f.read().decode(self.encoding)
            finally:
                f.close()

            self.loaded_filenames.add(filename)

            return super(FileSystemLoaderRecorder, self).get_source(
                environment, template)

        # If the template isn't found, then we have to drop out.
        raise TemplateNotFound(template)

def jinja_scanner(node, env, path):

    # Instantiate the file as necessary
    node.get_text_contents()

    node_dir = os.path.dirname(str(node))

    template_dir, filename = os.path.split(str(node))

    template_search_path = ([template_dir] +
                            env.subst(env['JINJA_TEMPLATE_SEARCHPATH']))
    template_loader = FileSystemLoaderRecorder(template_search_path)

    jinja_env = jinja2.Environment(loader=template_loader,
                                   extensions=['jinja2.ext.do'], **env['JINJA_ENVIRONMENT_VARS'])
    jinja_env.filters.update(env['JINJA_FILTERS'])
    jinja_env.globals.update(env['JINJA_GLOBALS'])

    try:
        template = jinja_env.get_template(filename)
    except TemplateNotFound as e:
        raise StopError('Missing template: ' +
                        os.path.join(template_dir, str(e)))

    # We need to render the template to do all the necessary loading.
    #
    # It's necessary to respond to missing templates by grabbing
    # the content as the exception is raised. This makes sure of the
    # existence of the file upon which the current scanned node depends.
    #
    # I suspect that this is pretty inefficient, but it does
    # work reliably.
    context = env['JINJA_CONTEXT']

    last_missing_file = ''
    while True:

        try:
            template.render(**context)
        except TemplateNotFound as e:
            if last_missing_file == str(e):
                # We've already been round once for this file,
                # so need to raise
                raise StopError('Missing template: ' +
                                os.path.join(template_dir, str(e)))

            last_missing_file = str(e)
            # Find where the template came from (using the same ordering
            # as Jinja uses).
            for searchpath in template_search_path:
                filename = os.path.join(searchpath, last_missing_file)
                if os.path.exists(filename):
                    continue
                else:
                    env.File(filename).get_text_contents()
            continue

        break

    # Get all the files that were loaded. The set includes the current node,
    # so we remove that.
    found_nodes_names = list(template_loader.loaded_filenames)
    try:
        found_nodes_names.remove(str(node))
    except ValueError as e:
        raise StopError('Missing template node: ' + str(node))

    return [env.File(f) for f in found_nodes_names]

def render_jinja_template(target, source, env):

    output_str = ''

    if not source:
        source = [f'{target}.jinja']

    for template_file in source:

        template_dir, filename = os.path.split(str(template_file))

        template_search_path = ([template_dir] +
                                env.subst(env['JINJA_TEMPLATE_SEARCHPATH']))
        template_loader = FileSystemLoaderRecorder(template_search_path)

        jinja_env = jinja2.Environment(loader=template_loader,
                                       extensions=['jinja2.ext.do'], **env['JINJA_ENVIRONMENT_VARS'])

        jinja_env.filters.update(env['JINJA_FILTERS'])
        jinja_env.globals.update(env['JINJA_GLOBALS'])
        template = jinja_env.get_template(filename)

        context = env['JINJA_CONTEXT']
        template.render(**context)

        output_str += template.render(**context)

    with open(str(target[0]), 'w') as target_file:
        target_file.write(output_str)

    return None

def generate(env):

    env.SetDefault(JINJA_CONTEXT={})
    env.SetDefault(JINJA_ENVIRONMENT_VARS={})
    env.SetDefault(JINJA_FILTERS={})
    env.SetDefault(JINJA_GLOBALS={})
    env.SetDefault(JINJA_TEMPLATE_SEARCHPATH=[])

    env['BUILDERS']['Jinja'] = SCons.Builder.Builder(
        action=render_jinja_template)

    scanner = env.Scanner(function=jinja_scanner,
                          skeys=['.jinja'])

    env.Append(SCANNERS=scanner)

def exists(env):
    try:
        import jinja2
    except ImportError as e:
        raise StopError(ImportError, e.message)