#
# This source code file is a merge of various build tools and a horrible mess.
#

from __future__ import annotations

import os
import pwd
import re
import sys

from enum import Enum, auto
from functools import lru_cache
from typing import TYPE_CHECKING

from .lib.App import App as Base
from .lib.Distro import Distro
from .lib.log import DEBUG, ERR, log

if TYPE_CHECKING:
    import argparse

    from typing import TypeAlias

    from .lib.ExecContext import ExecContext
    from .lib.PackageFilter import PackageFilter

# Meaning of pkg.requires.xxx variables
# build: needs to be built and installed before this can be built
# devel: needs to be installed before this-devel can be installed,
#        i.e. before _other_ packages can be built against this
# run:   needs to be installed before this-run can be installed,
#        i.e. before this and other packages can run with this

# --------------------------------------------------------------------- Helpers

class ResultCache(object):

    def __init__(self):
        self.__cache = {}

    def run(self, func, args):
        d = self.__cache
        depth = 0
        keys = [func.__name__] + args
        sz = len(keys)
        for k in keys:
            if k is None:
                k = 'None'
            else:
                k = str(k)
            depth += 1
            # log(DEBUG, 'depth = ', depth, 'key = ', k, 'd = ', str(d))
            if k in d:
                if sz == depth:
                    return d[k]
                d = d[k]
                continue
            if sz == depth:
                r = func(*args)
                d[k] = r
                return r
            d = d[k] = {}
            # d = d[k]
        raise Exception(
            'cache algorithm failed for function', func.__name__, 'in depth', depth
        )

class Scope(Enum):
    Self = auto()
    One = auto()
    Subtree = auto()

Graph: TypeAlias = dict[str, set[str]]

# ----------------------------------------------------------------- class App

class App(Base):

    def __format_topdir(self, path: None | str, fmt: str) -> str | None:
        if path is None:
            return None
        match fmt:
            case 'unaltered':
                return path
            case None | 'absolute':
                return os.path.abspath(path)
            case _:
                m = re.search(r'^make:(\S+)$', fmt)
                if m is None:
                    raise Exception(
                        f'Can\'t interpret "{fmt}" as valid topdir reference, '
                        'expecting "unaltered", "absolute", or "make:<variable-name>"'
                    )
                return '$(' + m.group(1) + ')'

    @property
    def __topdir(self) -> str:
        if self.___topdir is None:
            raise Exception('Tried to access undefined top directory')
        return self.___topdir

    @property
    def __pretty_topdir(self) -> str:
        if self.___pretty_topdir is None:
            raise Exception('Tried to access undefined pretty top directory')
        return self.___pretty_topdir

    def __proj_dir(self, name: str, pretty: bool) -> str | None:
        if name == self.__top_name:
            if pretty:
                return self.__pretty_topdir
            return self.__topdir
        for d in [self.__projs_root, '/opt']:
            ret = d + '/' + name
            if os.path.exists(ret):
                return ret
        if os.path.exists(f'/usr/share/doc/packages/{name}/VERSION'):
            # The package exists but does not have a dedicated project directory
            return None
        raise Exception('No project path found for module "{}"'.format(name))

    def __find_dir(
        self,
        name: str,
        search_subdirs: list[str] = [],
        search_absdirs: list[str] = [],
        pretty: bool = True,
    ) -> str | None:

        def format_pd(name: str, pd: str, pretty: bool):
            if not pretty:
                return pd
            if self.__topdir_fmt == 'absolute':
                return os.path.abspath(pd)
            if self.__topdir_fmt == 'unaltered':
                return pd
            if name == self.__top_name:
                return self.__pretty_topdir
            raise NotImplementedError(
                f'Tried to pretty-format directory {pd}, not implemented'
            )

        pd = self.__proj_dir(name, False)
        if pd is None:
            return None
        if not search_subdirs and not search_absdirs:
            return format_pd(name, pd, pretty)
        for sd in search_subdirs:
            path = pd + '/' + sd
            if os.path.isdir(path):
                ret = format_pd(name, pd, pretty)
                if sd and sd[0] != '/':
                    ret += '/'
                ret += sd
                return ret
        for ret in search_absdirs:
            if os.path.isdir(ret):
                return ret
        return None

    def __get_project_refs_cached(
        self, buf, visited, spec, section, key, add_self, scope, names_only
    ):
        return self.__res_cache.run(
            self.__get_project_refs,
            [buf, visited, spec, section, key, add_self, scope, names_only],
        )

    def __get_project_refs(
        self,
        buf: list[str],
        visited: set[str],
        spec: str,
        section: str,
        key: str,
        add_self: bool,
        scope: Scope,
        names_only: bool,
    ) -> None:
        name = self.strip_module_from_spec(spec)
        if names_only:
            spec = name
        if spec in buf:
            return
        if spec in visited:
            if add_self:
                buf.append(spec)
            return
        visited.add(spec)
        vals = self.get_value(name, section, key)
        log(
            DEBUG,
            (
                f'name={name}, section={section}, key={key}, deps={vals}, '
                f'scope={scope.name}, visited={visited}'
            ),
        )
        vals_list = vals.split(',') if vals else []
        match scope:
            case Scope.Self:
                buf += vals_list
            case Scope.One | Scope.Subtree:
                subscope = scope.Self if scope == Scope.One else scope
                for val in vals_list:
                    val = val.strip()
                    if not (len(val)):
                        continue
                    self.__get_project_refs_cached(
                        buf,
                        visited,
                        val,
                        section,
                        key,
                        add_self = True,
                        scope = subscope,
                        names_only = names_only,
                    )
        if add_self:
            buf.append(spec)

    def __read_dep_graph(
        self,
        projects: list[str],
        sections: str | list[str],
        graph: Graph,
    ) -> None:
        if isinstance(sections, str):
            sections = [sections]
        for project in projects:
            if project in graph:
                continue
            for section in sections:
                deps = self.get_project_refs(
                    [project],
                    ['pkg.requires.jw'],
                    sections,
                    scope = Scope.One,
                    add_self = False,
                    names_only = True,
                )
                if deps is None:
                    continue
                graph[project] = set(deps)
                for dep in deps:
                    self.__read_dep_graph([dep], sections, graph)

    def __flip_dep_graph(self, graph: Graph):
        ret: Graph = {}
        for project, deps in graph.items():
            for d in deps:
                if d not in ret:
                    ret[d] = set()
                ret[d].add(project)
        return ret

    def __find_circular_deps_recursive(
        self,
        project: str,
        graph: Graph,
        unvisited: list[str],
        temp: set[str],
        path: list[str],
    ) -> str | None:
        if project in temp:
            log(DEBUG, 'found circular dependency at project', project)
            return project
        if project not in unvisited:
            return None
        temp.add(project)
        if project in graph:
            for dep in graph[project]:
                last = self.__find_circular_deps_recursive(
                    dep, graph, unvisited, temp, path
                )
                if last is not None:
                    path.insert(0, dep)
                    return last
        unvisited.remove(project)
        temp.remove(project)
        return None

    def __find_circular_deps(self, projects: list[str], flavours: list[str]) -> bool:
        graph: Graph = {}
        ret: list[str] = []
        self.__read_dep_graph(projects, flavours, graph)
        unvisited = list(graph.keys())
        temp: set[str] = set()
        while unvisited:
            project = unvisited[0]
            log(DEBUG, 'Checking circular dependency of', project)
            last = self.__find_circular_deps_recursive(
                project, self.__flip_dep_graph(graph), unvisited, temp, ret
            )
            if last is not None:
                log(DEBUG, f'Found circular dependency below {project}, last is {last}')
                return True
        return False

    def __init__(self, distro: Distro | None = None) -> None:

        super().__init__('jw-pkg swiss army knife', modules = ['jw.pkg.cmds'])

        # -- Members without default values
        self.__opt_interactive: bool | None = None
        self.__opt_verbose: bool | None = None
        self.__top_name: str | None = None
        self.__distro = distro
        self.__res_cache = ResultCache()
        self.___topdir: str | None = None
        self.___pretty_topdir: str | None = None
        self.__exec_context: ExecContext | None = None

        # -- Members with default values
        self.__topdir_fmt = 'absolute'
        self.__projs_root = pwd.getpwuid(os.getuid()).pw_dir + '/local/src/jw.dev/proj'
        self.__pretty_projs_root = None

    async def __init_async(self) -> None:
        if self.__distro is None:
            pkg_filter_str = self.args.pkg_filter
            if pkg_filter_str is None:
                pkg_filter_str = os.getenv('JW_DEFAULT_PKG_FILTER')
            pkg_filter: PackageFilter | None = None
            if pkg_filter_str is not None:
                from .lib.PackageFilter import PackageFilterString

                pkg_filter = PackageFilterString(pkg_filter_str)
            self.__distro = await Distro.instantiate(
                ec = self.exec_context,
                id = self.args.distro_id,
                default_pkg_filter = pkg_filter,
            )

    async def __aexit__(self, exc_type, exc, tb) -> None:
        if self.__exec_context is not None:
            await self.__exec_context.close()
            self.__exec_context = None

    def _add_arguments(self, parser) -> None:
        super()._add_arguments(parser)
        parser.add_argument('-t', '--topdir', default = None, help = 'Project Path')
        parser.add_argument(
            '--topdir-format',
            default = 'absolute',
            help = (
                'Output references to topdir as one of "make:<var-name>", '
                '"unaltered", "absolute". Absolute topdir by default'
            ),
        )
        parser.add_argument(
            '-p',
            '--prefix',
            default = None,
            help = 'Parent directory of project source directories',
        )
        parser.add_argument(
            '--distro-id',
            default = None,
            help = 'Distribution ID (default is taken from /etc/os-release)',
        )
        parser.add_argument(
            '--interactive',
            choices = ['true', 'false', 'auto'],
            default = 'true',
            help = 'Wait for user input or try to proceed unattended',
        )
        parser.add_argument(
            '--verbose',
            action = 'store_true',
            default = False,
            help = "Be verbose on stderr about what's being done on the distro level",
        )
        parser.add_argument(
            '--target', default = 'local', help = 'Run commands on this host'
        )
        parser.add_argument(
            '--pkg-filter',
            help = 'Default filter for all distribution package-related operations',
        )

    async def _run(self, args: argparse.Namespace) -> None:
        self.___topdir = args.topdir
        self.___pretty_topdir = self.__format_topdir(self.___topdir, args.topdir_format)
        self.__topdir_fmt = args.topdir_format
        if self.___topdir is not None:
            self.__top_name = self.read_value(
                self.___topdir + '/make/project.conf', 'build', 'name'
            )
            if not self.__top_name:
                self.__top_name = re.sub(
                    '-[0-9.-]*$',
                    '',
                    os.path.basename(os.path.realpath(self.___topdir))
                )
        if args.prefix is not None:
            self.__projs_root = args.prefix
            self.__pretty_projs_root = args.prefix
        await self.__init_async()
        await super()._run(args)

    @property
    def interactive(self) -> bool:
        if self.__opt_interactive is None:
            match self.args.interactive:
                case 'true':
                    self.__opt_interactive = True
                case 'false':
                    self.__opt_interactive = False
                case 'auto':
                    self.__opt_interactive = sys.stdin.isatty()
                case _:
                    raise ValueError(
                        f'Unknown --interactive value: {self.args.interactive}'
                    )
            # Not logically possible to fail, but this keeps pyright happy
            assert self.__opt_interactive is not None
        return self.__opt_interactive

    @property
    def verbose(self) -> bool:
        if self.__opt_verbose is None:
            self.__opt_verbose = self.args.verbose
            # Not logically possible to fail, but this keeps pyright happy
            assert self.__opt_verbose is not None
        return self.__opt_verbose

    @property
    def exec_context(self) -> ExecContext:
        if self.__exec_context is None:
            from .lib.ExecContext import ExecContext

            self.__exec_context = ExecContext.create(
                self.args.target,
                interactive = self.interactive,
                verbose_default = self.verbose,
            )
        return self.__exec_context

    @property
    def top_name(self):
        return self.__top_name

    @property
    def projs_root(self):
        return self.__projs_root

    @property
    def distro(self) -> Distro:
        if self.__distro is None:
            raise Exception('No distro object')
        return self.__distro

    def find_dir(
        self,
        name: str,
        search_subdirs: list[str] = [],
        search_absdirs: list[str] = [],
        pretty: bool = True,
        throw: bool = False,
    ) -> str | None:
        ret = self.__find_dir(name, search_subdirs, search_absdirs, pretty)
        if ret is not None:
            return ret
        if not throw:
            return None
        msg = f'Failed to find directory for "{name}":'
        log(ERR, msg)
        for search_name, search in [
            ('subdirs', search_subdirs),
            ('absdirs', search_absdirs),
        ]:
            if search:
                log(ERR, f'Searched {search_name}:')
                for d in search:
                    log(ERR, f' - {d}')
        raise FileNotFoundError(msg)

    # TODO: add support for customizing this in project.conf
    def htdocs_dir(self, project: str) -> str | None:
        return self.find_dir(
            project,
            ['/src/html/htdocs', '/tools/html/htdocs', '/htdocs'],
            ['/srv/www/proj/' + project],
        )

    # TODO: add support for customizing this in project.conf
    def tmpl_dir(self, name: str) -> str | None:
        return self.find_dir(name, ['/tmpl'], ['/opt/' + name + '/share/tmpl'])

    def strip_module_from_spec(self, mod):
        return re.sub(r'-dev$|-devel$|-run$', '', re.split('([=><]+)', mod)[0].strip())

    @lru_cache(maxsize = None)
    def get_section(self, path: str, section: str) -> str:
        ret = ''
        pat = '[' + section + ']'
        in_section = False
        file = open(path)
        for line in file:
            if line.rstrip() == pat:
                in_section = True
                continue
            if in_section:
                if len(line) and line[0] == '[':
                    break
                ret += line
        file.close()
        return ret.rstrip()

    @lru_cache(maxsize = None)
    def read_value(self, path: str, section: str, key: str) -> str | None:

        def scan_section(f, key: str) -> str | None:
            if key is None:
                ret = ''
                for line in f:
                    if len(line) and line[0] == '[':
                        break
                    ret += line
                return ret if len(ret) else None
            lines: list[str] = []
            cont_line = ''
            for line in f:
                if len(line) and line[0] == '[':
                    break
                cont_line += line.rstrip()
                if len(cont_line) and cont_line[-1] == '\\':
                    cont_line = cont_line[0:-1]
                    continue
                lines.append(cont_line)
                cont_line = ''
            rx = re.compile(r'^\s*' + key + r'\s*=\s*(.*)\s*$')
            for line in lines:
                # log(DEBUG, '  looking for "%s" in line="%s"' % (key, line))
                m = re.search(rx, line)
                if m is not None:
                    return m.group(1)
            return None

        def scan_section_debug(f, key: str) -> str | None:
            ret = scan_section(f, key)
            # log(DEBUG, '  returning', rr)
            return ret

        try:
            # log(DEBUG, 'looking for {}::[{}].{}'.format(path, section, key))
            # TODO: Parse
            with open(path, 'r') as f:
                if not len(section):
                    return scan_section(f, key)
                pat = '[' + section + ']'
                for line in f:
                    if line.rstrip() == pat:
                        return scan_section(f, key)
                return None
        except Exception:
            log(DEBUG, f'Not found: {path}')
            # TODO: handle this special case cleaner somewhere up the stack
            if section == 'build' and key == 'libname':
                return 'none'
            return None

    @lru_cache(maxsize = None)
    def get_value(self, project: str, section: str, key: str) -> str | None:
        ret: str | None
        proj_dir = self.__proj_dir(project, pretty = False)
        if proj_dir is None:
            raise Exception(f"Can't get project directory for {project}")
        if section == 'version':
            proj_version_dirs = [proj_dir]
            if proj_dir != self.___topdir:
                proj_version_dirs.append('/usr/share/doc/packages/' + project)
            for d in proj_version_dirs:
                version_path = d + '/VERSION'
                try:
                    with open(version_path) as fd:
                        ret = fd.read().replace('\n', '').replace('-dev', '')
                        fd.close()
                        return ret
                except EnvironmentError:
                    log(DEBUG, f'Ignoring unreadable file "{version_path}"')
                    continue
            raise Exception(f'No version file found for project "{project}"')
        path = proj_dir + '/make/project.conf'
        ret = self.read_value(path, section, key)
        log(
            DEBUG,
            'Lookup %s -> %s / [%s%s] -> "%s"' %
            (self.__top_name, project, section, '.' + key if key else '', ret),
        )
        return ret

    @lru_cache(maxsize = None)
    def get_version(self, project) -> str:
        ret = self.get_value(project, 'version', '')
        if ret is None:
            raise Exception(f"Can't get version of project {project}")
        return ret

    def get_values(self, projects: list[str], sections: list[str],
                   keys: list[str]) -> list[str]:
        """
        Collect a list of values from a list of given projects, sections and
        keys, maintaining order
        """
        ret: list[str] = []
        for p in projects:
            for section in sections:
                for key in keys:
                    vals = self.get_value(p, section, key)
                    if vals:
                        ret += [val.strip() for val in vals.split(',')]
        return list(dict.fromkeys(ret))  # Remove duplicates, keep ordering

    def get_project_refs(
        self,
        projects: list[str],
        sections: list[str],
        keys: str | list[str],
        add_self: bool,
        scope: Scope,
        names_only = True,
    ) -> list[str]:
        if isinstance(keys, str):
            keys = [keys]
        ret: list[str] = []
        for section in sections:
            for key in keys:
                visited: set[str] = set()
                for name in projects:
                    rr: list[str] = []
                    self.__get_project_refs_cached(
                        rr, visited, name, section, key, add_self, scope, names_only
                    )
                    # TODO: this looks like a performance hogger
                    for m in rr:
                        if m not in ret:
                            ret.append(m)
        return ret

    def get_libname(self, projects) -> str:
        vals = self.get_project_refs(
            projects,
            ['build'],
            'libname',
            scope = Scope.One,
            add_self = False,
            names_only = True,
        )
        if not vals:
            return ' '.join(projects)
        if 'none' in vals:
            vals.remove('none')
        return ' '.join(reversed(vals))

    def is_excluded_from_build(self, project: str) -> str | None:
        log(DEBUG, 'checking if project ' + project + ' is excluded from build')
        exclude = self.get_value(project, 'build', 'exclude')
        if exclude is None:
            return None
        exclude_arr = re.split(r'[, ]+', exclude)
        cascade = self.distro.os_cascade + ['all']
        intersection = [x for x in cascade if x in set(exclude_arr)]
        if intersection:
            return ', '.join(intersection)
        return None

    def find_circular_deps(self, projects: list[str], flavours: list[str]) -> bool:
        return self.__find_circular_deps(projects, flavours)