import os

from datetime import datetime

from typing import List, Dict, Any, Optional, Union

from dataclasses import dataclass, asdict, field, fields


class ArchiveError(Exception):
    def __init__(self, message, hints=None):
        super().__init__(message)
        self.hints = hints

LinkDict = Dict[str, Any]

ArchiveOutput = Union[str, Exception, None]

@dataclass(frozen=True)
class ArchiveResult:
    cmd: List[str]
    pwd: Optional[str]
    cmd_version: Optional[str]
    output: ArchiveOutput
    status: str
    start_ts: datetime
    end_ts: datetime
    schema: str = 'ArchiveResult'

    def __post_init__(self):
        self.typecheck()

    def _asdict(self):
        return asdict(self)

    def typecheck(self) -> None:
        assert self.schema == self.__class__.__name__
        assert isinstance(self.status, str) and self.status
        assert isinstance(self.start_ts, datetime)
        assert isinstance(self.end_ts, datetime)
        assert isinstance(self.cmd, list)
        assert all(isinstance(arg, str) and arg for arg in self.cmd)
        assert self.pwd is None or isinstance(self.pwd, str) and self.pwd
        assert self.cmd_version is None or isinstance(self.cmd_version, str) and self.cmd_version
        assert self.output is None or isinstance(self.output, (str, Exception))
        if isinstance(self.output, str):
            assert self.output

    @classmethod
    def from_json(cls, json_info):
        from .util import parse_date

        allowed_fields = {f.name for f in fields(cls)}
        info = {
            key: val
            for key, val in json_info.items()
            if key in allowed_fields
        }
        info['start_ts'] = parse_date(info['start_ts'])
        info['end_ts'] = parse_date(info['end_ts'])
        return cls(**info)

    @property
    def duration(self) -> int:
        return (self.end_ts - self.start_ts).seconds

@dataclass(frozen=True)
class Link:
    timestamp: str
    url: str
    title: Optional[str]
    tags: Optional[str]
    sources: List[str]
    history: Dict[str, List[ArchiveResult]] = field(default_factory=lambda: {})
    updated: Optional[datetime] = None
    schema: str = 'Link'

    def __post_init__(self):
        self.typecheck()

    def overwrite(self, **kwargs):
        """pure functional version of dict.update that returns a new instance"""
        return Link(**{**self._asdict(), **kwargs})

    def __eq__(self, other):
        if not isinstance(other, Link):
            return NotImplemented
        return self.url == other.url

    def __gt__(self, other):
        if not isinstance(other, Link):
            return NotImplemented
        if not self.timestamp or not other.timestamp:
            return 
        return float(self.timestamp) > float(other.timestamp)

    def typecheck(self) -> None:
        assert self.schema == self.__class__.__name__
        assert isinstance(self.timestamp, str) and self.timestamp
        assert self.timestamp.replace('.', '').isdigit()
        assert isinstance(self.url, str) and '://' in self.url
        assert self.updated is None or isinstance(self.updated, datetime)
        assert self.title is None or isinstance(self.title, str) and self.title
        assert self.tags is None or isinstance(self.tags, str) and self.tags
        assert isinstance(self.sources, list)
        assert all(isinstance(source, str) and source for source in self.sources)
        assert isinstance(self.history, dict)
        for method, results in self.history.items():
            assert isinstance(method, str) and method
            assert isinstance(results, list)
            assert all(isinstance(result, ArchiveResult) for result in results)
    
    def _asdict(self, extended=False):
        info = {
            'schema': 'Link',
            'url': self.url,
            'title': self.title or None,
            'timestamp': self.timestamp,
            'updated': self.updated or None,
            'tags': self.tags or None,
            'sources': self.sources or [],
            'history': self.history or {},
        }
        if extended:
            info.update({
                'link_dir': self.link_dir,
                'archive_path': self.archive_path,
                'bookmarked_date': self.bookmarked_date,
                'updated_date': self.updated_date,
                'domain': self.domain,
                'path': self.path,
                'basename': self.basename,
                'extension': self.extension,
                'base_url': self.base_url,
                'is_static': self.is_static,
                'is_archived': self.is_archived,
                'num_outputs': self.num_outputs,
                'num_failures': self.num_failures,
                'oldest_archive_date': self.oldest_archive_date,
                'newest_archive_date': self.newest_archive_date,
            })
        return info

    @classmethod
    def from_json(cls, json_info):
        from .util import parse_date
        
        allowed_fields = {f.name for f in fields(cls)}
        info = {
            key: val
            for key, val in json_info.items()
            if key in allowed_fields
        }
        info['updated'] = parse_date(info['updated'])

        json_history = info['history']
        cast_history = {}

        for method, method_history in json_history.items():
            cast_history[method] = []
            for json_result in method_history:
                assert isinstance(json_result, dict), 'Items in Link["history"][method] must be dicts'
                cast_result = ArchiveResult.from_json(json_result)
                cast_history[method].append(cast_result)

        info['history'] = cast_history
        return cls(**info)


    @property
    def link_dir(self) -> str:
        from .config import ARCHIVE_DIR
        return os.path.join(ARCHIVE_DIR, self.timestamp)

    @property
    def archive_path(self) -> str:
        from .config import ARCHIVE_DIR_NAME
        return '{}/{}'.format(ARCHIVE_DIR_NAME, self.timestamp)
    
    ### URL Helpers
    @property
    def urlhash(self):
        from .util import hashurl

        return hashurl(self.url)

    @property
    def extension(self) -> str:
        from .util import extension
        return extension(self.url)

    @property
    def domain(self) -> str:
        from .util import domain
        return domain(self.url)

    @property
    def path(self) -> str:
        from .util import path
        return path(self.url)

    @property
    def basename(self) -> str:
        from .util import basename
        return basename(self.url)

    @property
    def base_url(self) -> str:
        from .util import base_url
        return base_url(self.url)

    ### Pretty Printing Helpers
    @property
    def bookmarked_date(self) -> Optional[str]:
        from .util import ts_to_date
        return ts_to_date(self.timestamp) if self.timestamp else None

    @property
    def updated_date(self) -> Optional[str]:
        from .util import ts_to_date
        return ts_to_date(self.updated) if self.updated else None

    @property
    def oldest_archive_date(self) -> Optional[datetime]:
        from .util import ts_to_date

        most_recent = min(
            (ts_to_date(result.start_ts)
             for method in self.history.keys()
                for result in self.history[method]),
            default=None,
        )
        return ts_to_date(most_recent) if most_recent else None

    @property
    def newest_archive_date(self) -> Optional[datetime]:
        from .util import ts_to_date

        most_recent = max(
            (ts_to_date(result.start_ts)
             for method in self.history.keys()
                for result in self.history[method]),
            default=None,
        )
        return ts_to_date(most_recent) if most_recent else None

    ### Archive Status Helpers
    @property
    def num_outputs(self) -> int:
        return len(tuple(filter(None, self.latest_outputs().values())))

    @property
    def num_failures(self) -> int:
        return sum(1
                   for method in self.history.keys()
                       for result in self.history[method]
                            if result.status == 'failed')

    @property
    def is_static(self) -> bool:
        from .util import is_static_file
        return is_static_file(self.url)

    @property
    def is_archived(self) -> bool:
        from .config import ARCHIVE_DIR
        from .util import domain

        return os.path.exists(os.path.join(
            ARCHIVE_DIR,
            self.timestamp,
            domain(self.url),
        ))

    def latest_outputs(self, status: str=None) -> Dict[str, ArchiveOutput]:
        """get the latest output that each archive method produced for link"""
        
        ARCHIVE_METHODS = (
            'title', 'favicon', 'wget', 'warc', 'pdf',
            'screenshot', 'dom', 'git', 'media', 'archive_org',
        )
        latest: Dict[str, ArchiveOutput] = {}
        for archive_method in ARCHIVE_METHODS:
            # get most recent succesful result in history for each archive method
            history = self.history.get(archive_method) or []
            history = list(filter(lambda result: result.output, reversed(history)))
            if status is not None:
                history = list(filter(lambda result: result.status == status, history))

            history = list(history)
            if history:
                latest[archive_method] = history[0].output
            else:
                latest[archive_method] = None

        return latest

    def canonical_outputs(self) -> Dict[str, Optional[str]]:
        from .util import wget_output_path
        canonical = {
            'index_url': 'index.html',
            'favicon_url': 'favicon.ico',
            'google_favicon_url': 'https://www.google.com/s2/favicons?domain={}'.format(self.domain),
            'archive_url': wget_output_path(self),
            'warc_url': 'warc',
            'pdf_url': 'output.pdf',
            'screenshot_url': 'screenshot.png',
            'dom_url': 'output.html',
            'archive_org_url': 'https://web.archive.org/web/{}'.format(self.base_url),
            'git_url': 'git',
            'media_url': 'media',
        }
        if self.is_static:
            # static binary files like PDF and images are handled slightly differently.
            # they're just downloaded once and aren't archived separately multiple times, 
            # so the wget, screenshot, & pdf urls should all point to the same file

            static_url = wget_output_path(self)
            canonical.update({
                'title': self.basename,
                'archive_url': static_url,
                'pdf_url': static_url,
                'screenshot_url': static_url,
                'dom_url': static_url,
            })
        return canonical