# Copyright (c) 2016 Weitian LI <liweitianux@live.com>
# MIT license

"""
Manage and manipulate the simulation products.
"""

import os
import shutil
import hashlib
import json
import logging
from collections import OrderedDict

import numpy as np

from .errors import ManifestError


logger = logging.getLogger(__name__)


class Products:
    """
    Manage and manipulate the simulation products.

    Attributes
    ----------
    manifest : dict
        The manifest of the simulation products.
        See the below "Manifest Format" section for more details.

    Manifest Format
    ---------------
    ``
    {
        "frequency" : {
            "frequencies" : [ <list of frequencies> ],
            "id" : [ <id/index of each frequency> ],
        },
        <component> : [
            {
                "frequency" : <frequency>,
                "healpix" : {
                    "path" : <relative path to healpix file>,
                    "size" : <file size (bytes)>,
                    "md5" : <md5 checksum>,
                },
                "hpx" : {
                    "path" : <relative path to converted HPX image>,
                    "size" : <file size (bytes)>,
                    "md5" : <md5 checksum>,
                },
            },
            ...
        ],
        ...
    }
    ``
    """
    def __init__(self, manifestfile=None):
        self.manifest = OrderedDict()
        self.manifestfile = None
        if manifestfile is not None:
            try:
                self.load(manifestfile)
            except FileNotFoundError:
                pass

    @property
    def frequencies(self):
        """
        Get the frequencies of the products from the manifest.
        """
        return self.manifest["frequency"]

    @frequencies.setter
    def frequencies(self, value):
        """
        Set the frequencies of the products and store in the manifest.

        Each frequency has an ID (also its index in the frequencies list).
        """
        self.manifest["frequency"] = {
            "frequencies": value,
            "id": range(len(value)),
        }
        logger.info("Number of frequencies: {0}".format(len(value)))

    def find_frequency_id(self, frequency, atol=1e-3):
        """
        Find the ID of the given frequency by comparing it to the
        frequencies list.

        Parameters
        ----------
        frequency : float
            The input frequency for which to find its the ID
        atol : float, optional
            The absolute tolerance parameter.
            For finite values, isclose uses the following equation to test
            whether two floating point values are equivalent:
                absolute(a - b) <= (atol + rtol * absolute(b))

        Returns
        -------
        id : int
            The ID of the input frequency, and ``-1`` if not found.
            ``None`` if frequencies currently not set.
        """
        try:
            frequencies = np.asarray(self.frequencies["frequencies"])
            fid = self.frequencies["id"]
            res = np.where(np.isclose(frequencies, frequency, atol=atol))[0]
            if len(res) == 0:
                return -1
            else:
                return fid[res[0]]
        except KeyError:
            # Frequencies currently not set
            return None

    def add_product(self, comp_id, freq_id, filepath):
        """
        Add one single simulation product to the manifest.

        The metadata (file path, size and MD5 checksum) of simulation
        products are stored in the manifest.

        Parameters
        ----------
        comp_id : str
            ID of the component to be added.
        freq_id : int
            Frequency ID
        filepath : str
            File path of the product (HEALPix maps).

        Raises
        ------
        ManifestError :
            * The attribute ``self.manifestfile`` is not set.
        """
        if self.manifestfile is None:
            raise ManifestError("'self.manifestfile' is not set")
        #
        frequencies = self.frequencies["frequencies"]
        if comp_id not in self.manifest.keys():
            # Initialize the manifest array for this component
            self.manifest[comp_id] = [{} for i in range(len(frequencies))]
        #
        curdir = os.path.dirname(self.manifestfile)
        self.manifest[comp_id][freq_id] = {
            "frequency": frequencies[freq_id],
            "healpix": {
                # Relative path to the HEALPix map file from this manifest
                "path": os.path.relpath(filepath, curdir),
                # File size in bytes
                "size": os.path.getsize(filepath),
                "md5": hashlib.md5(filepath).hexdigest(),
            }
        }
        logger.info("Added one product to the manifest: {0}".format(filepath))

    def add_component(self, comp_id, paths):
        """
        Add a simulation component to the manifest.

        The simulation products (file path, size and MD5 checksum) are
        stored in the manifest.

        Parameters
        ----------
        comp_id : str
            ID of the component to be added.
        paths : list[str]
            List of the file paths of the component products (HEALPix maps).
            The number of the paths must equal to the number of frequencies.

        Raises
        ------
        ManifestError :
            * The attribute ``self.manifestfile`` is not set.
            * Number of input paths dose NOT equal to number of frequencies
        """
        if self.manifestfile is None:
            raise ManifestError("'self.manifestfile' is not set")
        #
        frequencies = self.frequencies["frequencies"]
        if len(paths) != len(frequencies):
            raise ManifestError("Number of paths (%d) != " % len(paths) +
                                "number of frequencies")
        #
        for freq_id, filepath in enumerate(paths):
            self.add_product(comp_id, freq_id, filepath)
        logger.info("Added component '{0}' to the manifest".format(comp_id))

    def checksum(self, comp_id=None, freq_id=None):
        """
        Calculate the checksum for products and compare with the existing
        manifest.

        Parameters
        ----------
        comp_id : str
            ID of the component whose product will be checksum'ed
        freq_id : int
            The frequency ID of the specific product within the component.

        Returns
        -------
        match : bool
            Whether the MD5 checksum of the on-disk product matches the
            checksum stored in the manifest.
        hash : str
            The MD5 checksum value of the on-disk product.
        """
        curdir = os.path.dirname(self.manifestfile)
        metadata = self.manifest[comp_id][freq_id]
        filepath = os.path.join(curdir, metadata["healpix"]["path"])
        hash_true = metadata["healpix"]["md5"]
        hash_ondisk = hashlib.md5(filepath).hexdigest()
        if hash_ondisk == hash_true:
            match = True
        else:
            match = False
        return (match, hash_ondisk)

    def convert_hpx(self, comp_id, freq_id):
        """
        Convert the specified HEALPix map product to HPX projected FITS image.
        Also add the metadata of the HPX image to the manifest.
        """
        raise NotImplementedError("TODO")

    def dump(self, outfile, clobber=False, backup=True):
        """
        Dump the manifest as a JSON file.

        Parameters
        ----------
        outfile : str
            The path to the output manifest file.
            If not provided, then use ``self.manifestfile``.
            NOTE:
            This must be an *absolute path*.
            Prefix ``~`` (tilde) is allowed and will be expanded.
        clobber : bool, optional
            Overwrite the output file if already exists.
        backup : bool, optional
            Backup the output file with suffix ``.old`` if already exists.

        Raises
        ------
        ValueError :
            The given ``outfile`` is NOT an absolute path.
            Or the ``self.manifestfile`` is ``None`` while the ``outfile``
            is missing.
        OSError :
            If the target filename already exists and ``clobber=False``.
        """
        if outfile is None:
            if self.userconfig is None:
                raise ValueError("outfile is missing and " +
                                 "self.manifestfile is None")
            else:
                outfile = self.manifestfile
                logger.warning("outfile not provided, " +
                               "use self.manifestfile: {0}".format(outfile))
        outfile = os.path.expanduser(outfile)
        if not os.path.isabs(outfile):
            raise ValueError("Not an absolute path: {0}".format(outfile))
        if os.path.exists(outfile):
            if clobber:
                # Make a backup with suffix ``.old``
                backfile = outfile + ".old"
                shutil.copyfile(outfile, backfile)
            else:
                raise OSError("File already exists: {0}".format(outfile))
        #
        with open(outfile, "w") as fp:
            json.dump(self.manifest, fp, indent=4)
        logger.info("Dumped manifest to file: {0}".format(outfile))

    def load(self, infile):
        """
        Load the manifest from a JSON file.

        Parameters
        ----------
        infile : str
            The path to the input manifest file.
            NOTE:
            This must be an *absolute path*.
            Prefix ``~`` (tilde) is allowed and will be expanded.

        Raises
        ------
        ValueError :
            The given ``infile`` is NOT an absolute path.
        OSError :
            Cannot read the input manifest file.
        """
        infile = os.path.expanduser(infile)
        if not os.path.isabs(infile):
            raise ValueError("Not an absolute path: {0}".format(infile))
        # Keep the order of keys
        self.manifest = json.load(open(infile), object_pairs_hook=OrderedDict)
        logger.info("Loaded manifest from file: {0}".format(infile))