#!/usr/bin/env python

"""
Check lesson files and their contents.
"""

import sys
import os
import glob
import json
import re
from optparse import OptionParser

from util import Reporter, read_markdown, load_yaml, check_unwanted_files, require, IMAGE_FILE_SUFFIX

__version__ = '0.2'

# Where to look for source Markdown files.
SOURCE_DIRS = ['', '_episodes', '_extras']

# Required files: each entry is ('path': YAML_required).
# FIXME: We do not yet validate whether any files have the required
#   YAML headers, but should in the future.
# The '%' is replaced with the source directory path for checking.
# Episodes are handled specially, and extra files in '_extras' are also handled specially.
# This list must include all the Markdown files listed in the 'bin/initialize' script.
REQUIRED_FILES = {
    '%/CONDUCT.md': True,
    '%/CONTRIBUTING.md': False,
    '%/LICENSE.md': True,
    '%/README.md': False,
    '%/_extras/discuss.md': True,
    '%/_extras/figures.md': True,
    '%/_extras/guide.md': True,
    '%/index.md': True,
    '%/reference.md': True,
    '%/setup.md': True,
}

# Episode filename pattern.
P_EPISODE_FILENAME = re.compile(r'/_episodes/(\d\d)-[-\w]+.md$')

# Pattern to match lines ending with whitespace.
P_TRAILING_WHITESPACE = re.compile(r'\s+$')

# Pattern to match figure references in HTML.
P_FIGURE_REFS = re.compile(r'<img[^>]+src="([^"]+)"[^>]*>')

# What kinds of blockquotes are allowed?
KNOWN_BLOCKQUOTES = {
    'callout',
    'challenge',
    'checklist',
    'discussion',
    'keypoints',
    'objectives',
    'prereq',
    'quotation',
    'solution',
    'testimonial'
}

# What kinds of code fragments are allowed?
KNOWN_CODEBLOCKS = {
    'error',
    'output',
    'source',
    'bash',
    'make',
    'matlab',
    'python',
    'r',
    'sql'
}

# What fields are required in teaching episode metadata?
TEACHING_METADATA_FIELDS = {
    ('title', str),
    ('teaching', int),
    ('exercises', int),
    ('questions', list),
    ('objectives', list),
    ('keypoints', list)
}

# What fields are required in break episode metadata?
BREAK_METADATA_FIELDS = {
    ('layout', str),
    ('title', str),
    ('break', int)
}

# How long are lines allowed to be?
MAX_LINE_LEN = 100

def main():
    """Main driver."""

    args = parse_args()
    args.reporter = Reporter()
    check_config(args.reporter, args.source_dir)
    docs = read_all_markdown(args.source_dir, args.parser)
    check_fileset(args.source_dir, args.reporter, docs.keys())
    check_unwanted_files(args.source_dir, args.reporter)
    for filename in docs.keys():
        checker = create_checker(args, filename, docs[filename])
        checker.check()
    check_figures(args.source_dir, args.reporter)
    args.reporter.report()


def parse_args():
    """Parse command-line arguments."""

    parser = OptionParser()
    parser.add_option('-l', '--linelen',
                      default=False,
                      action="store_true",
                      dest='line_lengths',
                      help='Check line lengths')
    parser.add_option('-p', '--parser',
                      default=None,
                      dest='parser',
                      help='path to Markdown parser')
    parser.add_option('-s', '--source',
                      default=os.curdir,
                      dest='source_dir',
                      help='source directory')
    parser.add_option('-w', '--whitespace',
                      default=False,
                      action="store_true",
                      dest='trailing_whitespace',
                      help='Check for trailing whitespace')

    args, extras = parser.parse_args()
    require(args.parser is not None,
            'Path to Markdown parser not provided')
    require(not extras,
            'Unexpected trailing command-line arguments "{0}"'.format(extras))

    return args


def check_config(reporter, source_dir):
    """Check configuration file."""

    config_file = os.path.join(source_dir, '_config.yml')
    config = load_yaml(config_file)
    reporter.check_field(config_file, 'configuration', config, 'kind', 'lesson')
    reporter.check_field(config_file, 'configuration', config, 'carpentry', ('swc', 'dc'))
    reporter.check_field(config_file, 'configuration', config, 'title')
    reporter.check_field(config_file, 'configuration', config, 'email')
    reporter.check_field(config_file, 'configuration', config, 'repo')
    reporter.check_field(config_file, 'configuration', config, 'root')
    if ('repo' in config) and ('root' in config):
        reporter.check(config['repo'].endswith(config['root']),
                       config_file,
                       'Repository name "{0}" not consistent with root "{1}"',
                       config['repo'], config['root'])


def read_all_markdown(source_dir, parser):
    """Read source files, returning
    {path : {'metadata':yaml, 'metadata_len':N, 'text':text, 'lines':[(i, line, len)], 'doc':doc}}
    """

    all_dirs = [os.path.join(source_dir, d) for d in SOURCE_DIRS]
    all_patterns = [os.path.join(d, '*.md') for d in all_dirs]
    result = {}
    for pat in all_patterns:
        for filename in glob.glob(pat):
            data = read_markdown(parser, filename)
            if data:
                result[filename] = data
    return result


def check_fileset(source_dir, reporter, filenames_present):
    """Are all required files present? Are extraneous files present?"""

    # Check files with predictable names.
    required = [p.replace('%', source_dir) for p in REQUIRED_FILES]
    missing = set(required) - set(filenames_present)
    for m in missing:
        reporter.add(None, 'Missing required file {0}', m)

    # Check episode files' names.
    seen = []
    for filename in filenames_present:
        if '_episodes' not in filename:
            continue
        m = P_EPISODE_FILENAME.search(filename)
        if m and m.group(1):
            seen.append(m.group(1))
        else:
            reporter.add(None, 'Episode {0} has badly-formatted filename', filename)

    # Check for duplicate episode numbers.
    reporter.check(len(seen) == len(set(seen)),
                        None,
                        'Duplicate episode numbers {0} vs {1}',
                        sorted(seen), sorted(set(seen)))

    # Check that numbers are consecutive.
    seen = [int(s) for s in seen]
    seen.sort()
    clean = True
    for i in range(len(seen) - 1):
        clean = clean and ((seen[i+1] - seen[i]) == 1)
    reporter.check(clean,
                   None,
                   'Missing or non-consecutive episode numbers {0}',
                   seen)


def check_figures(source_dir, reporter):
    """Check that all figures are present and referenced."""

    # Get references.
    try:
        all_figures_html = os.path.join(source_dir, '_includes', 'all_figures.html')
        with open(all_figures_html, 'r') as reader:
            text = reader.read()
        figures = P_FIGURE_REFS.findall(text)
        referenced = [os.path.split(f)[1] for f in figures if '/fig/' in f]
    except FileNotFoundError as e:
        reporter.add(all_figures_html,
                     'File not found')
        return

    # Get actual image files (ignore non-image files).
    fig_dir_path = os.path.join(source_dir, 'fig')
    actual = [f for f in os.listdir(fig_dir_path) if os.path.splitext(f)[1] in IMAGE_FILE_SUFFIX]

    # Report differences.
    unexpected = set(actual) - set(referenced)
    reporter.check(not unexpected,
                   None,
                   'Unexpected image files: {0}',
                   ', '.join(sorted(unexpected)))
    missing = set(referenced) - set(actual)
    reporter.check(not missing,
                   None,
                   'Missing image files: {0}',
                   ', '.join(sorted(missing)))


def create_checker(args, filename, info):
    """Create appropriate checker for file."""

    for (pat, cls) in CHECKERS:
        if pat.search(filename):
            return cls(args, filename, **info)


class CheckBase(object):
    """Base class for checking Markdown files."""

    def __init__(self, args, filename, metadata, metadata_len, text, lines, doc):
        """Cache arguments for checking."""

        super(CheckBase, self).__init__()
        self.args = args
        self.reporter = self.args.reporter # for convenience
        self.filename = filename
        self.metadata = metadata
        self.metadata_len = metadata_len
        self.text = text
        self.lines = lines
        self.doc = doc

        self.layout = None


    def check(self):
        """Run tests on metadata."""

        self.check_metadata()
        self.check_line_lengths()
        self.check_trailing_whitespace()
        self.check_blockquote_classes()
        self.check_codeblock_classes()


    def check_metadata(self):
        """Check the YAML metadata."""

        self.reporter.check(self.metadata is not None,
                            self.filename,
                            'Missing metadata entirely')

        if self.metadata and (self.layout is not None):
            self.reporter.check_field(self.filename, 'metadata', self.metadata, 'layout', self.layout)


    def check_line_lengths(self):
        """Check the raw text of the lesson body."""

        if self.args.line_lengths:
            over = [i for (i, l, n) in self.lines if (n > MAX_LINE_LEN) and (not l.startswith('!'))]
            self.reporter.check(not over,
                                self.filename,
                                'Line(s) are too long: {0}',
                                ', '.join([str(i) for i in over]))


    def check_trailing_whitespace(self):
        """Check for whitespace at the ends of lines."""

        if self.args.trailing_whitespace:
            trailing = [i for (i, l, n) in self.lines if P_TRAILING_WHITESPACE.match(l)]
            self.reporter.check(not trailing,
                                self.filename,
                                'Line(s) end with whitespace: {0}',
                                ', '.join([str(i) for i in trailing]))


    def check_blockquote_classes(self):
        """Check that all blockquotes have known classes."""

        for node in self.find_all(self.doc, {'type' : 'blockquote'}):
            cls = self.get_val(node, 'attr', 'class')
            self.reporter.check(cls in KNOWN_BLOCKQUOTES,
                                (self.filename, self.get_loc(node)),
                                'Unknown or missing blockquote type {0}',
                                cls)


    def check_codeblock_classes(self):
        """Check that all code blocks have known classes."""

        for node in self.find_all(self.doc, {'type' : 'codeblock'}):
            cls = self.get_val(node, 'attr', 'class')
            self.reporter.check(cls in KNOWN_CODEBLOCKS,
                                (self.filename, self.get_loc(node)),
                                'Unknown or missing code block type {0}',
                                cls)


    def find_all(self, node, pattern, accum=None):
        """Find all matches for a pattern."""

        assert type(pattern) == dict, 'Patterns must be dictionaries'
        if accum is None:
            accum = []
        if self.match(node, pattern):
            accum.append(node)
        for child in node.get('children', []):
            self.find_all(child, pattern, accum)
        return accum


    def match(self, node, pattern):
        """Does this node match the given pattern?"""

        for key in pattern:
            if key not in node:
                return False
            val = pattern[key]
            if type(val) == str:
                if node[key] != val:
                    return False
            elif type(val) == dict:
                if not self.match(node[key], val):
                    return False
        return True


    def get_val(self, node, *chain):
        """Get value one or more levels down."""

        curr = node
        for selector in chain:
            curr = curr.get(selector, None)
            if curr is None:
                break
        return curr


    def get_loc(self, node):
        """Convenience method to get node's line number."""

        result = self.get_val(node, 'options', 'location')
        if self.metadata_len is not None:
            result += self.metadata_len
        return result


class CheckNonJekyll(CheckBase):
    """Check a file that isn't translated by Jekyll."""

    def __init__(self, args, filename, metadata, metadata_len, text, lines, doc):
        super(CheckNonJekyll, self).__init__(args, filename, metadata, metadata_len, text, lines, doc)


    def check_metadata(self):
        self.reporter.check(self.metadata is None,
                            self.filename,
                            'Unexpected metadata')


class CheckIndex(CheckBase):
    """Check the main index page."""

    def __init__(self, args, filename, metadata, metadata_len, text, lines, doc):
        super(CheckIndex, self).__init__(args, filename, metadata, metadata_len, text, lines, doc)
        self.layout = 'lesson'


class CheckEpisode(CheckBase):
    """Check an episode page."""

    def __init__(self, args, filename, metadata, metadata_len, text, lines, doc):
        super(CheckEpisode, self).__init__(args, filename, metadata, metadata_len, text, lines, doc)

    def check_metadata(self):
        super(CheckEpisode, self).check_metadata()
        if self.metadata:
            if 'layout' in self.metadata:
                if self.metadata['layout'] == 'break':
                    self.check_metadata_fields(BREAK_METADATA_FIELDS)
                else:
                    self.reporter.add(self.filename,
                                      'Unknown episode layout "{0}"',
                                      self.metadata['layout'])
            else:
                self.check_metadata_fields(TEACHING_METADATA_FIELDS)


    def check_metadata_fields(self, expected):
        for (name, type_) in expected:
            if name not in self.metadata:
                self.reporter.add(self.filename,
                                  'Missing metadata field {0}',
                                  name)
            elif type(self.metadata[name]) != type_:
                self.reporter.add(self.filename,
                                  '"{0}" has wrong type in metadata ({1} instead of {2})',
                                  name, type(self.metadata[name]), type_)


class CheckReference(CheckBase):
    """Check the reference page."""

    def __init__(self, args, filename, metadata, metadata_len, text, lines, doc):
        super(CheckReference, self).__init__(args, filename, metadata, metadata_len, text, lines, doc)
        self.layout = 'reference'


class CheckGeneric(CheckBase):
    """Check a generic page."""

    def __init__(self, args, filename, metadata, metadata_len, text, lines, doc):
        super(CheckGeneric, self).__init__(args, filename, metadata, metadata_len, text, lines, doc)
        self.layout = 'page'


CHECKERS = [
    (re.compile(r'CONTRIBUTING\.md'), CheckNonJekyll),
    (re.compile(r'README\.md'), CheckNonJekyll),
    (re.compile(r'index\.md'), CheckIndex),
    (re.compile(r'reference\.md'), CheckReference),
    (re.compile(r'_episodes/.*\.md'), CheckEpisode),
    (re.compile(r'.*\.md'), CheckGeneric)
]


if __name__ == '__main__':
    main()