#!/usr/bin/env python2
# vim:fileencoding=utf-8
# License: GPLv3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>

from __future__ import (unicode_literals, division, absolute_import,
                        print_function)
from hashlib import sha1
from functools import partial
from threading import RLock, Lock
from cPickle import dumps
from zipfile import ZipFile
import errno, os, tempfile, shutil, time, json as jsonlib

from lzma.xz import decompress
from calibre.constants import cache_dir, iswindows
from calibre.customize.ui import plugin_for_input_format
from calibre.srv.metadata import book_as_json
from calibre.srv.render_book import RENDER_VERSION
from calibre.srv.errors import HTTPNotFound, BookNotFound
from calibre.srv.routes import endpoint, json
from calibre.srv.utils import get_library_data, get_db

cache_lock = RLock()
queued_jobs = {}
failed_jobs = {}


def abspath(x):
    x = os.path.abspath(x)
    if iswindows and not x.startswith('\\\\?\\'):
        x = '\\\\?\\' + os.path.abspath(x)
    return x


_books_cache_dir = None


def books_cache_dir():
    global _books_cache_dir
    if _books_cache_dir:
        return _books_cache_dir
    base = abspath(os.path.join(cache_dir(), 'srvb'))
    for d in 'sf':
        try:
            os.makedirs(os.path.join(base, d))
        except EnvironmentError as e:
            if e.errno != errno.EEXIST:
                raise
    _books_cache_dir = base
    return base


def book_hash(library_uuid, book_id, fmt, size, mtime):
    raw = dumps((library_uuid, book_id, fmt.upper(), size, mtime, RENDER_VERSION))
    return sha1(raw).hexdigest().decode('ascii')


staging_cleaned = False


def safe_remove(x, is_file=None):
    if is_file is None:
        is_file = os.path.isfile(x)
    try:
        os.remove(x) if is_file else shutil.rmtree(x, ignore_errors=True)
    except EnvironmentError:
        pass


def queue_job(ctx, copy_format_to, bhash, fmt, book_id, size, mtime):
    global staging_cleaned
    tdir = os.path.join(books_cache_dir(), 's')
    if not staging_cleaned:
        staging_cleaned = True
        for x in os.listdir(tdir):
            safe_remove(os.path.join(tdir, x))
    fd, pathtoebook = tempfile.mkstemp(prefix='', suffix=('.' + fmt.lower()), dir=tdir)
    with os.fdopen(fd, 'wb') as f:
        copy_format_to(f)
    tdir = tempfile.mkdtemp('', '', tdir)
    job_id = ctx.start_job('Render book %s (%s)' % (book_id, fmt), 'calibre.srv.render_book', 'render', args=(
        pathtoebook, tdir, {'size':size, 'mtime':mtime, 'hash':bhash}),
        job_done_callback=job_done, job_data=(bhash, pathtoebook, tdir))
    queued_jobs[bhash] = job_id
    return job_id


last_final_clean_time = 0


def clean_final(interval=24 * 60 * 60):
    global last_final_clean_time
    now = time.time()
    if now - last_final_clean_time < interval:
        return
    last_final_clean_time = now
    fdir = os.path.join(books_cache_dir(), 'f')
    for x in os.listdir(fdir):
        try:
            tm = os.path.getmtime(os.path.join(fdir, x,  'calibre-book-manifest.json'))
        except EnvironmentError:
            continue
        if now - tm >= interval:
            # This book has not been accessed for a long time, delete it
            safe_remove(x)


def job_done(job):
    with cache_lock:
        bhash, pathtoebook, tdir = job.data
        queued_jobs.pop(bhash, None)
        safe_remove(pathtoebook)
        if job.failed:
            failed_jobs[bhash] = (job.was_aborted, job.traceback)
            safe_remove(tdir, False)
        else:
            try:
                clean_final()
                dest = os.path.join(books_cache_dir(), 'f', bhash)
                safe_remove(dest, False)
                os.rename(tdir, dest)
            except Exception:
                import traceback
                failed_jobs[bhash] = (False, traceback.format_exc())


@endpoint('/book-manifest/{book_id}/{fmt}', postprocess=json, types={'book_id':int})
def book_manifest(ctx, rd, book_id, fmt):
    db, library_id = get_library_data(ctx, rd)[:2]
    force_reload = rd.query.get('force_reload') == '1'
    if plugin_for_input_format(fmt) is None:
        raise HTTPNotFound('The format %s cannot be viewed' % fmt.upper())
    if not ctx.has_id(rd, db, book_id):
        raise BookNotFound(book_id, db)
    with db.safe_read_lock:
        fm = db.format_metadata(book_id, fmt)
        if not fm:
            raise HTTPNotFound('No %s format for the book (id:%s) in the library: %s' % (fmt, book_id, library_id))
        size, mtime = map(int, (fm['size'], time.mktime(fm['mtime'].utctimetuple())*10))
        bhash = book_hash(db.library_id, book_id, fmt, size, mtime)
        with cache_lock:
            mpath = abspath(os.path.join(books_cache_dir(), 'f', bhash, 'calibre-book-manifest.json'))
            if force_reload:
                safe_remove(mpath, True)
            try:
                os.utime(mpath, None)
                with lopen(mpath, 'rb') as f:
                    ans = jsonlib.load(f)
                ans['metadata'] = book_as_json(db, book_id)
                user = rd.username or None
                ans['last_read_positions'] = db.get_last_read_positions(book_id, fmt, user)
                return ans
            except EnvironmentError as e:
                if e.errno != errno.ENOENT:
                    raise
            x = failed_jobs.pop(bhash, None)
            if x is not None:
                return {'aborted':x[0], 'traceback':x[1], 'job_status':'finished'}
            job_id = queued_jobs.get(bhash)
            if job_id is None:
                job_id = queue_job(ctx, partial(db.copy_format_to, book_id, fmt), bhash, fmt, book_id, size, mtime)
    status, result, tb, aborted = ctx.job_status(job_id)
    return {'aborted': aborted, 'traceback':tb, 'job_status':status, 'job_id':job_id}


@endpoint('/book-file/{book_id}/{fmt}/{size}/{mtime}/{+name}', types={'book_id':int, 'size':int, 'mtime':int})
def book_file(ctx, rd, book_id, fmt, size, mtime, name):
    db, library_id = get_library_data(ctx, rd)[:2]
    if not ctx.has_id(rd, db, book_id):
        raise BookNotFound(book_id, db)
    bhash = book_hash(db.library_id, book_id, fmt, size, mtime)
    base = abspath(os.path.join(books_cache_dir(), 'f'))
    mpath = abspath(os.path.join(base, bhash, name))
    if not mpath.startswith(base):
        raise HTTPNotFound('No book file with hash: %s and name: %s' % (bhash, name))
    try:
        return rd.filesystem_file_with_custom_etag(lopen(mpath, 'rb'), bhash, name)
    except EnvironmentError as e:
        if e.errno != errno.ENOENT:
            raise
        raise HTTPNotFound('No book file with hash: %s and name: %s' % (bhash, name))


@endpoint('/book-get-last-read-position/{library_id}/{+which}', postprocess=json)
def get_last_read_position(ctx, rd, library_id, which):
    '''
    Get last read position data for the specified books, where which is of the form:
    book_id1-fmt1_book_id2-fmt2,...
    '''
    db = get_db(ctx, rd, library_id)
    user = rd.username or None
    ans = {}
    allowed_book_ids = ctx.allowed_book_ids(rd, db)
    for item in which.split('_'):
        book_id, fmt = item.partition('-')[::2]
        try:
            book_id = int(book_id)
        except Exception:
            continue
        if book_id not in allowed_book_ids:
            continue
        key = '{}:{}'.format(book_id, fmt)
        ans[key] = db.get_last_read_positions(book_id, fmt, user)
    return ans


@endpoint('/book-set-last-read-position/{library_id}/{book_id}/{+fmt}', types={'book_id': int}, methods=('POST',))
def set_last_read_position(ctx, rd, library_id, book_id, fmt):
    db = get_db(ctx, rd, library_id)
    user = rd.username or None
    if not ctx.has_id(rd, db, book_id):
        raise BookNotFound(book_id, db)
    try:
        data = jsonlib.load(rd.request_body_file)
        device, cfi, pos_frac = data['device'], data['cfi'], data['pos_frac']
    except Exception:
        raise HTTPNotFound('Invalid data')
    db.set_last_read_position(
        book_id, fmt, user=user, device=device, cfi=cfi or None, pos_frac=pos_frac)
    rd.outheaders['Content-type'] = 'text/plain'
    return b''


mathjax_lock = Lock()
mathjax_manifest = None


def get_mathjax_manifest(tdir=None):
    global mathjax_manifest
    with mathjax_lock:
        if mathjax_manifest is None:
            mathjax_manifest = {}
            f = decompress(P('content-server/mathjax.zip.xz', data=True, allow_user_override=False))
            f.seek(0)
            tdir = os.path.join(tdir, 'mathjax')
            os.mkdir(tdir)
            zf = ZipFile(f)
            zf.extractall(tdir)
            mathjax_manifest['etag'] = type('')(zf.comment)
            mathjax_manifest['files'] = {type('')(zi.filename):zi.file_size for zi in zf.infolist()}
            zf.close(), f.close()
        return mathjax_manifest


def manifest_as_json():
    ans = jsonlib.dumps(get_mathjax_manifest(), ensure_ascii=False)
    if not isinstance(ans, bytes):
        ans = ans.encode('utf-8')
    return ans


@endpoint('/mathjax/{+which=""}', auth_required=False)
def mathjax(ctx, rd, which):
    manifest = get_mathjax_manifest(rd.tdir)
    if not which:
        return rd.etagged_dynamic_response(manifest['etag'], manifest_as_json, content_type='application/json; charset=UTF-8')
    if which not in manifest['files']:
        raise HTTPNotFound('No MathJax file named: %s' % which)
    path = os.path.abspath(os.path.join(rd.tdir, 'mathjax', which))
    if not path.startswith(rd.tdir):
        raise HTTPNotFound('No MathJax file named: %s' % which)
    return rd.filesystem_file_with_constant_etag(lopen(path, 'rb'), manifest['etag'])
