import datetime
import random

from flask import Blueprint, current_app, render_template, request, session, redirect, url_for, abort
try:
    import markdown
    has_markdown = True
except ImportError:
    has_markdown = False
import pygments
from pygments import highlight
from pygments.lexers import get_all_lexers, get_lexer_by_name
from pygments.formatters import HtmlFormatter

from . import db

app = Blueprint(__name__, 'pastepy')

base62_alphabet = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'

class PasteError(Exception): pass
class UnknownSyntaxError(PasteError): pass

class CustomHtmlFormatter(HtmlFormatter):
    def wrap(self, source, outfile):
        yield 0, '<pre>'
        line = 1
        for i, t in source:
            yield i, '<span id="codeline-{}">{}</span>'.format(i, t)
            line += 1
        yield 0, '</pre>'

def init_lexers():
    all_lexers = dict([(x[0], x[1][0]) for x in get_all_lexers()])
    lexers = []
    removed = []
    for cat, ls in current_app.config['CATEGORIES']:
        for l in ls:
            removed.append(l)
        lexers.append((cat, [(x, all_lexers[x]) for x in ls if x in all_lexers]))
    for l in removed:
        try:
            del all_lexers[l]
        except KeyError:
            pass
    rendered = []
    if has_markdown:
        rendered.append(('Rendered markdown', 'md-render'))
    if len(rendered):
        lexers.append(('Rendered', rendered))
    lexers.append(('Others' if current_app.config['CATEGORIES'] else 'Syntax', sorted(all_lexers.items(), key = lambda l: l[0].lower())))

    current_app.config['LEXERS'] = lexers
    current_app.config['FORMATTER'] = CustomHtmlFormatter(linenos='table', lineanchors='line', anchorlinenos=True)

init_lexers()

@app.route('/')
@app.route('/paste')
def paste():
    context = {
        'title': current_app.config['PASTEBIN_NAME'],
        'header': current_app.config['PASTEBIN_NAME'],
    }
    return render_template('paste.html', **context)

def get_formatted(syntax, text):
    if syntax == 'md-render' and has_markdown:
        text = markdown.markdown(text, extensions=current_app.config['MARKDOWN_EXTENSIONS'])
        lexername = 'Rendered markdown'
    else:
        try:
            lex = get_lexer_by_name(syntax or 'text')
        except pygments.util.ClassNotFound:
            raise UnknownSyntaxError(syntax)
        lexername = lex.name
        text = highlight(text, lex, current_app.config['FORMATTER'])
    return (lexername, text)

def add_paste():
    nick = request.form.get('nick')
    syntax = request.form.get('syntax')
    title = request.form.get('title')
    text = request.form.get('text').replace('\r', '')

    with db.session_scope() as db_session:
        paste_hash = ''.join(random.choice(base62_alphabet) for x in range(5))
        paste = db.Paste(paste_hash, nick, datetime.datetime.utcnow(), syntax, title, text, request.remote_addr)
        db_session.add(paste)

    if 'remember_me' in request.form:
        session['nick'] = nick
    else:
        session.pop('nick', None)
    if 'remember_syntax' in request.form:
        session['syntax'] = syntax
    else:
        session.pop('syntax', None)
    return redirect(url_for('.view_paste', paste_hash=paste_hash))

def render_preview():
    try:
        lexername, text = get_formatted(request.form['syntax'], request.form['text'])
    except UnknownSyntaxError:
        abort(500, 'Could not find lexer "{}".'.format(request.form['syntax']))

    nick = request.form['nick'] or 'Anonymous'
    title = request.form['title'] or 'Untitled'
    return render_template('view.html',
        title='Preview',
        hash=None,
        nick=nick,
        date='{} UTC'.format(datetime.datetime.utcnow().ctime()),
        syntax=lexername,
        pastetitle=title,
        text=text,
        rendered=(lexername or '').startswith('Rendered '),
    )

@app.route('/paste', methods=['POST'])
def post_paste():
    if request.form['type'] == 'Preview':
        return render_preview()
    if request.form['type'] == 'Paste':
        return add_paste()
    abort(404)

@app.route('/view/<paste_hash>')
@app.route('/full/<paste_hash>', endpoint='view_full')
def view_paste(paste_hash):
    with db.session_scope() as db_session:
        try:
            cache = db_session.query(db.Cache).filter_by(paste_hash=paste_hash).one()
            paste = cache.paste
        except db.NoResultFound:
            try:
                paste = db_session.query(db.Paste).filter_by(hash=paste_hash).one()
            except db.NoResultFound:
                abort(404)
            try:
                lexername, text = get_formatted(paste.syntax, paste.text)
            except UnknownSyntaxError:
                abort(500, 'Could not find the lexer "{}"'.format(paste.syntax))
            cache = db.Cache(paste_hash, lexername, text)
            db_session.add(cache)
    template = 'full.html' if request.endpoint.endswith('.view_full') else 'view.html'
    return render_template(template,
        title='View paste \u2013 {}'.format(paste.title or 'Untitled'),
        hash=paste_hash,
        date='{} UTC'.format(paste.date.ctime()),
        nick=paste.nick or 'Anonymous',
        syntax=cache.syntax_name,
        pastetitle=paste.title or 'Untitled',
        text=cache.text,
        rendered=(cache.syntax_name or '').startswith('Rendered '),
    )

@app.route('/highlight_stylesheet')
def highlight_stylesheet():
    return current_app.config['FORMATTER'].get_style_defs(), 200, {'Content-Type': 'text/css'}

@app.route('/raw/<paste_hash>')
def raw(paste_hash):
    with db.session_scope() as db_session:
        try:
            paste = db_session.query(db.Paste).filter_by(hash=paste_hash).one()
        except db.NoResultFound:
            abort(404)
    return paste.text, 200, {'Content-Type': 'text/plain'}