__all__ = ["Dependency", "Metadata"]

import collections
import copy
import json
import re
import subprocess


Requirement = collections.namedtuple('Requirement', ('kind',
                                                     'version'))


Version = collections.namedtuple('Version', ('major', 'minor',
                                             'patch', 'pre_release',
                                             'build'))


class CargoSemVer:
    """Cargo semantic versioning parser"""
    KIND_ANY = '*'
    KIND_LT = '<'
    KIND_LTE = '<='
    KIND_SHORTEQ = '='
    KIND_EQUAL = '=='
    KIND_EMPTY = ''
    KIND_GTE = '>='
    KIND_GT = '>'
    KIND_NEQ = '!='
    KIND_CARET = '^'
    KIND_TILDE = '~'
    KIND_COMPATIBLE = '~='

    def __init__(self, requirement):
        requirements = requirement.replace(' ', '').split(',')
        self.requirements = [self.parse(i) for i in requirements]
        self.normalized = [j for i in self.requirements
                           for j in self.normalize(i)]

    @staticmethod
    def parse(requirement):
        if not requirement:
            raise ValueError(f'Invalid empty requirement '
                             f'specification: {requirement}')

        match = re.match(
            r'^(?:([\d.\*]*\*))$|^(?:(<|<=|=|==|>=|>||!=|\^|~|~=)(\d.*))$',
            requirement)
        if not match:
            raise ValueError(f'Invalid requirement '
                             f'specification: {requirement}')

        wildcard, kind, version = match.groups()
        if wildcard:
            version = wildcard.replace('.*', '').replace('*', '')
            kind = CargoSemVer.KIND_ANY
        return Requirement(kind, CargoSemVer.parse_version(version))

    @staticmethod
    def parse_version(version):
        match = re.match(
            r'^(\d+)?(?:\.(\d+))?(?:\.(\d+))?(?:-([\w.-]+))?(?:\+([\w.-]+))?$',
            version)
        if not match:
            raise ValueError(f'Invalid version string: {version}')

        major, minor, patch, pre_release, build = match.groups()
        major = int(major) if major else major
        minor = int(minor) if minor else minor
        patch = int(patch) if patch else patch
        return Version(major, minor, patch, pre_release, build)

    @staticmethod
    def unparse_version(version, sep='-'):
        version_str = f'{version.major}.{version.minor or 0}' \
            f'.{version.patch or 0}'
        if version.pre_release:
            version_str = f'{version_str}{sep}{version.pre_release}'
        if version.build:
            version_str = f'{version_str}+{version.build}'
        return version_str

    @staticmethod
    def coerce(version):
        return Version(version.major or 0,
                       version.minor or 0,
                       version.patch or 0,
                       version.pre_release,
                       version.build)

    @staticmethod
    def next_major(version):
        major, minor, patch, pre_release, _ = version
        if pre_release and not minor and not patch:
            return Version(major, minor or 0, patch or 0, None, None)
        return Version((major or 0) + 1, 0, 0, None, None)

    @staticmethod
    def next_minor(version):
        major, minor, patch, pre_release, _ = version
        if pre_release and not patch:
            return Version(major, minor or 0, patch or 0, None, None)
        return Version(major, (minor or 0) + 1, 0, None, None)

    @staticmethod
    def next_patch(version):
        major, minor, patch, pre_release, _ = version
        if pre_release:
            return Version(major, minor or 0, patch or 0, None, None)
        return Version(major, minor or 0, (patch or 0) + 1, None, None)

    @staticmethod
    def normalize(requirement):
        normalized = []
        kind, version = requirement
        if kind == CargoSemVer.KIND_NEQ:
            raise ValueError(f'Kind not supported: {requirement}')

        if kind == CargoSemVer.KIND_EQUAL:
            kind = CargoSemVer.KIND_SHORTEQ

        coerced_version = CargoSemVer.coerce(version)
        if version.pre_release:
            version = CargoSemVer.next_patch(version)

        if kind == CargoSemVer.KIND_ANY:
            normalized.append((CargoSemVer.KIND_GTE,
                               CargoSemVer.coerce(version)))
            if version.major:
                if version.minor is not None:
                    upper_version = CargoSemVer.next_minor(version)
                else:
                    upper_version = CargoSemVer.next_major(version)
                normalized.append((CargoSemVer.KIND_LT, upper_version))
        elif kind in (CargoSemVer.KIND_SHORTEQ,
                      CargoSemVer.KIND_GT, CargoSemVer.KIND_GTE,
                      CargoSemVer.KIND_LT, CargoSemVer.KIND_LTE):
            normalized.append((kind, coerced_version))
        elif kind in (CargoSemVer.KIND_CARET,
                      CargoSemVer.KIND_COMPATIBLE,
                      CargoSemVer.KIND_EMPTY):
            if version.major == 0:
                if version.minor is not None:
                    if version.minor != 0 or version.patch is None:
                        upper_version = CargoSemVer.next_minor(version)
                    else:
                        upper_version = CargoSemVer.next_patch(version)
                else:
                    upper_version = CargoSemVer.next_major(version)
            else:
                upper_version = CargoSemVer.next_major(version)
            normalized.append((CargoSemVer.KIND_GTE, coerced_version))
            normalized.append((CargoSemVer.KIND_LT, upper_version))
        elif kind == CargoSemVer.KIND_TILDE:
            if version.minor is None:
                upper_version = CargoSemVer.next_major(version)
            else:
                upper_version = CargoSemVer.next_minor(version)
            normalized.append((CargoSemVer.KIND_GTE, coerced_version))
            normalized.append((CargoSemVer.KIND_LT, upper_version))
        else:
            raise ValueError(f'Found unhandled kind: {requirement}')
        return normalized


class Target:
    def __init__(self, name, kind):
        self.name = name
        self.kind = kind

    def __repr__(self):
        return f"<Target {self.name} ({self.kind})>"


class Dependency:
    def __init__(self, name, req=None, features=(), optional=False):
        self.name = name
        self.req = req
        self.features = features
        self.optional = optional

    @classmethod
    def from_json(cls, metadata):
        features = set(metadata["features"])
        if metadata["uses_default_features"]:
            features.add("default")
        kwargs = {"name": metadata["name"],
                  "req": metadata["req"],
                  "optional": metadata["optional"],
                  "features": features}
        return cls(**kwargs)

    @staticmethod
    def _apply_reqs(name, reqs, feature=None):
        fstr = f"/{feature}" if feature is not None else ""
        cap = f"crate({name}{fstr})"
        if not reqs:
            return cap
        deps = ' with '.join(
            f'{cap} {op} {CargoSemVer.unparse_version(version, sep="~")}'
            for op, version in reqs)
        if len(reqs) > 1:
            return f"({deps})"
        else:
            return deps

    def normalize(self):
        semver = CargoSemVer(self.req)
        return [self._apply_reqs(self.name, semver.normalized, feature)
                for feature in self.features or (None,)]

    def __repr__(self):
        return f"<Dependency: {self.name} {self.req} ({', '.join(sorted(self.features))})>"

    def __str__(self):
        return "\n".join(self.normalize())


class Metadata:
    def __init__(self, name, version):
        self.name = name
        coerced_version = CargoSemVer.coerce(CargoSemVer.parse_version(version))
        self._version = CargoSemVer.unparse_version(coerced_version)
        self.version = CargoSemVer.unparse_version(coerced_version, sep="~")
        self.license = None
        self.license_file = None
        self.readme = None
        self._description = None
        self._summary = None
        self.targets = set()
        self.dependencies = {}
        self.dev_dependencies = set()

    @property
    def description(self):
        return self._description

    @property
    def summary(self):
        return self._summary

    @description.setter
    def description(self, description):
        # https://salsa.debian.org/rust-team/debcargo/blob/master/src/crates.rs
        # get_summary_description()
        if description is None:
            self._description = self._summary = None
            return
        description = description.replace('\n\n', '\r').replace('\n', ' ').replace('\r', '\n').strip()
        description = re.sub(rf'^(?:{self.name}|This(?:\s+\w+)?)(?:\s*,|\s+is|\s+provides)\s+', '', description, flags=re.I)
        description = re.sub(r'^(?:a|an|the)\s+', '', description, flags=re.I)
        description = f'{description[0].upper()}{description[1:]}'
        if description[-1] != '.':
            description = f'{description}.'

        p1 = description.find('.')
        p2 = description.find('.\n')
        if p2 != -1:
            p1 = max(p1, p2)
        else:
            p1 = len(description) - 1
        p2 = description.find('. ')
        if p2 != -1:
            p1 = min(p1, p2)
        p2 = description.find('\n')
        if p2 != -1:
            p = min(p1, p2)
        else:
            p = p1

        self._description = description
        self._summary = description[:p]

    @classmethod
    def from_json(cls, metadata):
        md = metadata
        self = cls(md["name"], md["version"])

        self.license = md["license"]
        self.license_file = md["license_file"]
        self.readme = md["readme"]
        self.description = md.get("description")

        # dependencies + build-dependencies → runtime
        deps_by_name = collections.defaultdict(list)
        for dep in md["dependencies"]:
            if dep["kind"] == "dev":
                continue
            deps_by_name[dep["rename"] or dep["name"]].append(Dependency.from_json(dep))

        deps_by_feature = {}
        local_features = set(md["features"]) | set(
            d["rename"] for d in md["dependencies"] if d["rename"] is not None
        )
        for feature, f_deps in md["features"].items():
            features = {None}
            deps = set()
            for dep in f_deps:
                if dep in local_features:
                    features.add(dep)
                else:
                    pkg, _, f = dep.partition("/")
                    for dep in deps_by_name[pkg]:
                        dep = copy.deepcopy(dep)
                        if f:
                            dep.features = {f}
                        deps.add(dep)
            deps_by_feature[feature] = (features, deps)

        mandatory_deps = set()
        for name, deps in deps_by_name.items():
            fdeps = set()
            for dep in deps:
                if dep.optional:
                    fdeps.add(copy.deepcopy(dep))
                else:
                    mandatory_deps.add(copy.deepcopy(dep))
            if fdeps:
                deps_by_feature[name] = ({None}, fdeps)
        deps_by_feature[None] = (set(), mandatory_deps)

        if "default" not in deps_by_feature:
            deps_by_feature["default"] = ({None}, set())

        self.dependencies = deps_by_feature
        self.dev_dependencies = {Dependency.from_json(dep)
                                 for dep in md["dependencies"]
                                 if dep["kind"] == "dev"}

        self.targets = {Target(tgt["name"], tgt["kind"][0])
                        for tgt in md["targets"]}

        return self

    @classmethod
    def from_file(cls, path):
        metadata = subprocess.check_output(["cargo", "read-manifest",
                                            f"--manifest-path={path}"])
        return cls.from_json(json.loads(metadata))

    @property
    def all_dependencies(self):
        return set().union(*(x[1] for x in self.dependencies.values()))

    def provides(self, feature=None):
        if feature not in self.dependencies:
            raise KeyError(f"Feature {feature!r} doesn't exist")
        return Dependency(self.name, f"={self._version}", features={feature})

    @classmethod
    def _resolve(cls, deps_by_feature, feature):
        all_features = set()
        all_deps = set()
        ff, dd = copy.deepcopy(deps_by_feature[feature])
        all_features |= ff
        all_deps |= dd
        for f in ff:
            ff1, dd1 = cls._resolve(deps_by_feature, f)
            all_features |= ff1
            all_deps |= dd1
        return all_features, all_deps

    def requires(self, feature=None, resolve=False):
        if resolve:
            return self._resolve(self.dependencies, feature)[1]
        else:
            features, deps = self.dependencies[feature]
            fdeps = set(Dependency(self.name, f"={self._version}", features={feature})
                        for feature in features)
            return fdeps | deps


def normalize_deps(deps):
    return set().union(*(d.normalize() for d in deps))