import os
import re
import copy
import json
import pprint

import pyblish.api
from avalon import api


def collect(root,
            regex=None,
            exclude_regex=None,
            startFrame=None,
            endFrame=None):
    """Collect sequence collections in root"""

    from avalon.vendor import clique

    files = list()
    for filename in os.listdir(root):

        # Must have extension
        ext = os.path.splitext(filename)[1]
        if not ext:
            continue

        # Only files
        if not os.path.isfile(os.path.join(root, filename)):
            continue

        # Include and exclude regex
        if regex and not re.search(regex, filename):
            continue
        if exclude_regex and re.search(exclude_regex, filename):
            continue

        files.append(filename)

    # Match collections
    # Support filenames like: projectX_shot01_0010.tiff with this regex
    pattern = r"(?P<index>(?P<padding>0*)\d+)\.\D+\d?$"
    collections, remainder = clique.assemble(files,
                                             patterns=[pattern],
                                             minimum_items=1)

    # Ignore any remainders
    if remainder:
        print("Skipping remainder {}".format(remainder))

    # Exclude any frames outside start and end frame.
    for collection in collections:
        for index in list(collection.indexes):
            if startFrame is not None and index < startFrame:
                collection.indexes.discard(index)
                continue
            if endFrame is not None and index > endFrame:
                collection.indexes.discard(index)
                continue

    # Keep only collections that have at least a single frame
    collections = [c for c in collections if c.indexes]

    return collections


class CollectFileSequences(pyblish.api.ContextPlugin):
    """Gather file sequences from working directory

    When "FILESEQUENCE" environment variable is set these paths (folders or
    .json files) are parsed for image sequences. Otherwise the current
    working directory is searched for file sequences.

    The json configuration may have the optional keys:
        asset (str): The asset to publish to. If not provided fall back to
            api.Session["AVALON_ASSET"]
        subset (str): The subset to publish to. If not provided the sequence's
            head (up to frame number) will be used.
        startFrame (int): The start frame for the sequence
        endFrame (int): The end frame for the sequence
        root (str): The path to collect from (can be relative to the .json)
        regex (str): A regex for the sequence filename
        exclude_regex (str): A regex for filename to exclude from collection
        metadata (dict): Custom metadata for instance.data["metadata"]

    """

    order = pyblish.api.CollectorOrder
    targets = ["filesequence"]
    label = "File Sequences"
    hosts = ['maya']

    def process(self, context):

        if os.environ.get("FILESEQUENCE"):
            paths = os.environ["FILESEQUENCE"].split(os.pathsep)
        else:
            cwd = context.get("workspaceDir", os.getcwd())
            paths = [cwd]

        for path in paths:

            self.log.info("Loading: {}".format(path))

            if path.endswith(".json"):
                # Search using .json configuration
                with open(path, "r") as f:
                    try:
                        data = json.load(f)
                    except Exception as exc:
                        self.log.error("Error loading json: "
                                       "{} - Exception: {}".format(path, exc))
                        raise

                cwd = os.path.dirname(path)
                root_override = data.get("root")
                if root_override:
                    if os.path.isabs(root_override):
                        root = root_override
                    else:
                        root = os.path.join(cwd, root_override)
                else:
                    root = cwd

            else:
                # Search in directory
                data = dict()
                root = path

            self.log.info("Collecting: {}".format(root))
            regex = data.get("regex")
            if regex:
                self.log.info("Using regex: {}".format(regex))

            collections = collect(root=root,
                                  regex=regex,
                                  exclude_regex=data.get("exclude_regex"),
                                  startFrame=data.get("startFrame"),
                                  endFrame=data.get("endFrame"))

            self.log.info("Found collections: {}".format(collections))

            if data.get("subset"):
                # If subset is provided for this json then it must be a single
                # collection.
                if len(collections) > 1:
                    self.log.error("Forced subset can only work with a single "
                                   "found sequence")
                    raise RuntimeError("Invalid sequence")

            # Get family from the data
            families = data.get("families", ["imagesequence"])
            assert isinstance(families, (list, tuple)), "Must be iterable"
            assert families, "Must have at least a single family"

            for collection in collections:
                instance = context.create_instance(str(collection))
                self.log.info("Collection: %s" % list(collection))

                # Ensure each instance gets a unique reference to the data
                data = copy.deepcopy(data)

                # If no subset provided, get it from collection's head
                subset = data.get("subset", collection.head.rstrip("_. "))

                # If no start or end frame provided, get it from collection
                indices = list(collection.indexes)
                start = data.get("startFrame", indices[0])
                end = data.get("endFrame", indices[-1])

                instance.data.update({
                    "name": str(collection),
                    "family": families[0],  # backwards compatibility / pyblish
                    "families": list(families),
                    "subset": subset,
                    "asset": data.get("asset", api.Session["AVALON_ASSET"]),
                    "stagingDir": root,
                    "files": [list(collection)],
                    "startFrame": start,
                    "endFrame": end
                })
                instance.append(collection)

                self.log.debug("Collected instance:\n"
                               "{}".format(pprint.pformat(instance.data)))
