import os
import re
import sys
from itertools import chain
from typing import (
    BinaryIO,
    Dict,
    Iterable,
    Iterator,
    List,
    Optional,
    Set,
    Tuple,
    Union,
    cast,
)

from click import unstyle
from click.core import Context
from pip._internal.models.format_control import FormatControl
from pip._internal.req.req_install import InstallRequirement
from pip._vendor.packaging.markers import Marker
from pip._vendor.packaging.utils import canonicalize_name

from .logging import log
from .utils import (
    UNSAFE_PACKAGES,
    comment,
    dedup,
    format_requirement,
    get_compile_command,
    key_from_ireq,
    strip_extras,
)

MESSAGE_UNHASHED_PACKAGE = comment(
    "# WARNING: pip install will require the following package to be hashed."
    "\n# Consider using a hashable URL like "
    "https://github.com/jazzband/pip-tools/archive/SOMECOMMIT.zip"
)

MESSAGE_UNSAFE_PACKAGES_UNPINNED = comment(
    "# WARNING: The following packages were not pinned, but pip requires them to be"
    "\n# pinned when the requirements file includes hashes. "
    "Consider using the --allow-unsafe flag."
)

MESSAGE_UNSAFE_PACKAGES = comment(
    "# The following packages are considered to be unsafe in a requirements file:"
)

MESSAGE_UNINSTALLABLE = (
    "The generated requirements file may be rejected by pip install. "
    "See # WARNING lines for details."
)


strip_comes_from_line_re = re.compile(r" \(line \d+\)$")


def _comes_from_as_string(comes_from: Union[str, InstallRequirement]) -> str:
    if isinstance(comes_from, str):
        return strip_comes_from_line_re.sub("", comes_from)
    return cast(str, canonicalize_name(key_from_ireq(comes_from)))


def annotation_style_split(required_by: Set[str]) -> str:
    sorted_required_by = sorted(required_by)
    if len(sorted_required_by) == 1:
        source = sorted_required_by[0]
        annotation = "# via " + source
    else:
        annotation_lines = ["# via"]
        for source in sorted_required_by:
            annotation_lines.append("    #   " + source)
        annotation = "\n".join(annotation_lines)
    return annotation


def annotation_style_line(required_by: Set[str]) -> str:
    return f"# via {', '.join(sorted(required_by))}"


class OutputWriter:
    def __init__(
        self,
        dst_file: BinaryIO,
        click_ctx: Context,
        dry_run: bool,
        emit_header: bool,
        emit_index_url: bool,
        emit_trusted_host: bool,
        annotate: bool,
        annotation_style: str,
        strip_extras: bool,
        generate_hashes: bool,
        default_index_url: str,
        index_urls: Iterable[str],
        trusted_hosts: Iterable[str],
        format_control: FormatControl,
        allow_unsafe: bool,
        find_links: List[str],
        emit_find_links: bool,
        emit_options: bool,
    ) -> None:
        self.dst_file = dst_file
        self.click_ctx = click_ctx
        self.dry_run = dry_run
        self.emit_header = emit_header
        self.emit_index_url = emit_index_url
        self.emit_trusted_host = emit_trusted_host
        self.annotate = annotate
        self.annotation_style = annotation_style
        self.strip_extras = strip_extras
        self.generate_hashes = generate_hashes
        self.default_index_url = default_index_url
        self.index_urls = index_urls
        self.trusted_hosts = trusted_hosts
        self.format_control = format_control
        self.allow_unsafe = allow_unsafe
        self.find_links = find_links
        self.emit_find_links = emit_find_links
        self.emit_options = emit_options

    def _sort_key(self, ireq: InstallRequirement) -> Tuple[bool, str]:
        return (not ireq.editable, key_from_ireq(ireq))

    def write_header(self) -> Iterator[str]:
        if self.emit_header:
            yield comment("#")
            yield comment(
                "# This file is autogenerated by pip-compile with python "
                f"{sys.version_info.major}.{sys.version_info.minor}"
            )
            yield comment("# To update, run:")
            yield comment("#")
            compile_command = os.environ.get(
                "CUSTOM_COMPILE_COMMAND"
            ) or get_compile_command(self.click_ctx)
            yield comment(f"#    {compile_command}")
            yield comment("#")

    def write_index_options(self) -> Iterator[str]:
        if self.emit_index_url:
            for index, index_url in enumerate(dedup(self.index_urls)):
                if index == 0 and index_url.rstrip("/") == self.default_index_url:
                    continue
                flag = "--index-url" if index == 0 else "--extra-index-url"
                yield f"{flag} {index_url}"

    def write_trusted_hosts(self) -> Iterator[str]:
        if self.emit_trusted_host:
            for trusted_host in dedup(self.trusted_hosts):
                yield f"--trusted-host {trusted_host}"

    def write_format_controls(self) -> Iterator[str]:
        for nb in dedup(sorted(self.format_control.no_binary)):
            yield f"--no-binary {nb}"
        for ob in dedup(sorted(self.format_control.only_binary)):
            yield f"--only-binary {ob}"

    def write_find_links(self) -> Iterator[str]:
        if self.emit_find_links:
            for find_link in dedup(self.find_links):
                yield f"--find-links {find_link}"

    def write_flags(self) -> Iterator[str]:
        if not self.emit_options:
            return
        emitted = False
        for line in chain(
            self.write_index_options(),
            self.write_find_links(),
            self.write_trusted_hosts(),
            self.write_format_controls(),
        ):
            emitted = True
            yield line
        if emitted:
            yield ""

    def _iter_lines(
        self,
        results: Set[InstallRequirement],
        unsafe_requirements: Optional[Set[InstallRequirement]] = None,
        markers: Optional[Dict[str, Marker]] = None,
        hashes: Optional[Dict[InstallRequirement, Set[str]]] = None,
    ) -> Iterator[str]:
        # default values
        unsafe_requirements = unsafe_requirements or set()
        markers = markers or {}
        hashes = hashes or {}

        # Check for unhashed or unpinned packages if at least one package does have
        # hashes, which will trigger pip install's --require-hashes mode.
        warn_uninstallable = False
        has_hashes = hashes and any(hash for hash in hashes.values())

        yielded = False

        for line in self.write_header():
            yield line
            yielded = True
        for line in self.write_flags():
            yield line
            yielded = True

        unsafe_requirements = (
            {r for r in results if r.name in UNSAFE_PACKAGES}
            if not unsafe_requirements
            else unsafe_requirements
        )
        packages = {r for r in results if r.name not in UNSAFE_PACKAGES}

        if packages:
            for ireq in sorted(packages, key=self._sort_key):
                if has_hashes and not hashes.get(ireq):
                    yield MESSAGE_UNHASHED_PACKAGE
                    warn_uninstallable = True
                line = self._format_requirement(
                    ireq, markers.get(key_from_ireq(ireq)), hashes=hashes
                )
                yield line
            yielded = True

        if unsafe_requirements:
            yield ""
            yielded = True
            if has_hashes and not self.allow_unsafe:
                yield MESSAGE_UNSAFE_PACKAGES_UNPINNED
                warn_uninstallable = True
            else:
                yield MESSAGE_UNSAFE_PACKAGES

            for ireq in sorted(unsafe_requirements, key=self._sort_key):
                ireq_key = key_from_ireq(ireq)
                if not self.allow_unsafe:
                    yield comment(f"# {ireq_key}")
                else:
                    line = self._format_requirement(
                        ireq, marker=markers.get(ireq_key), hashes=hashes
                    )
                    yield line

        # Yield even when there's no real content, so that blank files are written
        if not yielded:
            yield ""

        if warn_uninstallable:
            log.warning(MESSAGE_UNINSTALLABLE)

    def write(
        self,
        results: Set[InstallRequirement],
        unsafe_requirements: Set[InstallRequirement],
        markers: Dict[str, Marker],
        hashes: Optional[Dict[InstallRequirement, Set[str]]],
    ) -> None:

        for line in self._iter_lines(results, unsafe_requirements, markers, hashes):
            if self.dry_run:
                # Bypass the log level to always print this during a dry run
                log.log(line)
            else:
                log.info(line)
                self.dst_file.write(unstyle(line).encode())
                self.dst_file.write(os.linesep.encode())

    def _format_requirement(
        self,
        ireq: InstallRequirement,
        marker: Optional[Marker] = None,
        hashes: Optional[Dict[InstallRequirement, Set[str]]] = None,
    ) -> str:
        ireq_hashes = (hashes if hashes is not None else {}).get(ireq)

        line = format_requirement(ireq, marker=marker, hashes=ireq_hashes)
        if self.strip_extras:
            line = strip_extras(line)

        if not self.annotate:
            return line

        # Annotate what packages or reqs-ins this package is required by
        required_by = set()
        if hasattr(ireq, "_source_ireqs"):
            required_by |= {
                _comes_from_as_string(src_ireq.comes_from)
                for src_ireq in ireq._source_ireqs
                if src_ireq.comes_from
            }

        if ireq.comes_from:
            required_by.add(_comes_from_as_string(ireq.comes_from))

        required_by |= set(getattr(ireq, "_required_by", set()))

        if required_by:
            if self.annotation_style == "split":
                annotation = annotation_style_split(required_by)
                sep = "\n    "
            elif self.annotation_style == "line":
                annotation = annotation_style_line(required_by)
                sep = "\n    " if ireq_hashes else "  "
            else:  # pragma: no cover
                raise ValueError("Invalid value for annotation style")
            if self.strip_extras:
                annotation = strip_extras(annotation)
            # 24 is one reasonable column size to use here, that we've used in the past
            lines = f"{line:24}{sep}{comment(annotation)}".splitlines()
            line = "\n".join(ln.rstrip() for ln in lines)

        return line
