# Copyright (c) 2016-2017 Weitian LI <weitian@aaronly.me>
# MIT license

"""
Manage and manipulate the simulation products.

XXX/TODO: update with HEALPix and sky patch, according to ``sky.py``.
"""

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

import numpy as np

from .errors import ManifestError
from .utils.hashutil import calc_md5


logger = logging.getLogger(__name__)


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

    Parameters
    ----------
    manifestfile : str, optional
        The absolute path to the manifest file for loading.
    load : bool, optional
        Load the specified manifest file if ``True``.

    Attributes
    ----------
    manifest : dict
        The manifest of the simulation products.
        See the below "Manifest Format" section for more details.
    manifestfile : str
        The absolute path to the loaded manifest file.

    Manifest Format
    ---------------
    ``
    {
        "frequency" : {
            "frequencies" : [ <list of frequencies> ],
            "id" : [ <id/index of each frequency> ],
            "unit": <frequency unit>,
        },
        <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, load=True):
        self.manifest = OrderedDict()
        self.manifestfile = manifestfile
        if (manifestfile is not None) and load:
            self.load(manifestfile)

    @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).

        Parameters
        ----------
        value : list[float], or tuple(list[float], str)
            The list of simulation frequencies, or a tuple of the frequencies
            and its unit (default: MHz).
        """
        if isinstance(value, tuple) and len(value) == 2:
            frequencies, unit = value
        else:
            frequencies = value
            unit = "MHz"
        #
        self.manifest["frequency"] = {
            "frequencies": list(frequencies),
            "id": list(range(len(frequencies))),
            "unit": unit,
        }
        logger.info("Number of frequencies: {0}, ".format(len(frequencies)) +
                    "unit: {0}".format(unit))

    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))]
        #
        root_dir = self.get_root_dir()
        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, root_dir),
                # File size in bytes
                "size": os.path.getsize(filepath),
                "md5": calc_md5(filepath),
            }
        }
        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, freq_id):
        """
        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.
        """
        root_dir = self.get_root_dir()
        metadata = self.get_product(comp_id, freq_id)
        filepath = os.path.join(root_dir, metadata["healpix"]["path"])
        hash_true = metadata["healpix"]["md5"]
        hash_ondisk = calc_md5(filepath)
        if hash_ondisk == hash_true:
            match = True
        else:
            match = False
        return (match, hash_ondisk)

    def get_root_dir(self):
        """
        Get the root directory where the products locate, which is also
        the directory where the manifest file locates.

        Returns
        -------
        root_dir : str
            The absolute path of the products root directory.

        Raises
        ------
        ManifestError :
            The manifest currently not loaded, thus unable to determine
            the products root directory.
        """
        try:
            return os.path.dirname(self.manifestfile)
        except AttributeError:
            raise ManifestError("Manifest currently not loaded!")

    def get_product(self, comp_id, freq_id):
        return self.manifest[comp_id][freq_id]

    def get_product_abspath(self, comp_id, freq_id, ptype="healpix"):
        """
        Get the absolute path to the specified product.

        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.
        ptype : str, optional
            The type of product whose path will be retrieved.
            Valid values: ``healpix`` (default), ``hpx``.

        Returns
        -------
        abspath : str
            The absolute path to the specified product

        Raises
        ------
        ValueError :
            Invalid ``ptype`` other than ``healpix`` and ``hpx``.
        KeyError :
            The requested product type not available (e.g., the HPX
            image is not generated yet)
        """
        if ptype not in ["healpix", "hpx"]:
            raise ValueError("Invalid ptype: {0}".format(ptype))
        root_dir = self.get_root_dir()
        metadata = self.get_product(comp_id, freq_id)
        abspath = os.path.join(root_dir, metadata[ptype]["path"])
        return abspath

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

        Raises
        ------
        IOError :
            Output HPX image already exists and ``clobber=False``
        """
        from astropy.io import fits
        from .utils.healpix import healpix2hpx
        #
        root_dir = self.get_root_dir()
        metadata = self.get_product(comp_id, freq_id)
        infile = os.path.join(root_dir, metadata["healpix"]["path"])
        outfile = os.path.splitext(infile)[0] + "_hpx.fits"
        if os.path.exists(outfile):
            if clobber:
                os.remove(outfile)
                logger.warning("Removed existing HPX image: %s" % outfile)
            else:
                raise IOError("Output HPX image already exists: %s" % outfile)
        # Convert HEALPix map to HPX projected FITS image
        logger.info("Converting HEALPix map to HPX image: %s" % infile)
        hpx_data, hpx_header = healpix2hpx(infile)
        hdu = fits.PrimaryHDU(data=hpx_data, header=hpx_header)
        hdu.writeto(outfile)
        logger.info("Converted HEALPix map to HPX image: %s" % outfile)
        #
        size = os.path.getsize(outfile)
        md5 = calc_md5(outfile)
        metadata["hpx"] = {
            "path": os.path.relpath(outfile, root_dir),
            "size": size,
            "md5": md5,
        }
        return (outfile, size, md5)

    def reset(self):
        self.manifest = OrderedDict()
        self.manifestfile = None
        logger.warning("Reset products manifest!")

    def dump(self, outfile=None, clobber=False, backup=True):
        """
        Dump the manifest as a JSON file.

        Parameters
        ----------
        outfile : str, optional
            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.manifestfile is None:
                raise ValueError("outfile is missing and " +
                                 "self.manifestfile is None")
            else:
                outfile = self.manifestfile
                logger.info("Output to 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)
                logger.info("Backed up old manifest file as: " + backfile)
            else:
                raise OSError("File already exists: {0}".format(outfile))
        #
        with open(outfile, "w") as fp:
            json.dump(self.manifest, fp, indent=4)
            fp.write("\n")
        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))
        # Reset existing manifest
        self.reset()
        # Keep the order of keys
        self.manifest = json.load(open(infile), object_pairs_hook=OrderedDict)
        self.manifestfile = infile
        logger.info("Loaded manifest from file: {0}".format(infile))