from __future__ import annotations

import asyncio
import logging
from collections import defaultdict
from typing import Any

from yuxi.channel.secrets.models import (
    DEFAULT_SECRET_PROVIDER_ALIAS,
    SecretIssue,
    SecretRef,
    SecretResolveResult,
    SecretSource,
    is_secret_ref,
    is_valid_exec_secret_ref_id,
    parse_secret_ref,
    secret_ref_key,
    validate_ref_id,
)
from yuxi.channel.secrets.providers import (
    EnvProvider,
    ExecProvider,
    FileProvider,
    SecretsProvider,
)

logger = logging.getLogger(__name__)

DEFAULT_PROVIDER_CONCURRENCY = 4
DEFAULT_MAX_REFS_PER_PROVIDER = 512


def _provider_key(source: SecretSource, alias: str | None = None) -> str:
    return f"{source.value}:{alias or DEFAULT_SECRET_PROVIDER_ALIAS}"


def _parse_provider_key(key: str) -> tuple[SecretSource, str] | None:
    parts = key.split(":", 1)
    if len(parts) != 2:
        return None
    try:
        return SecretSource(parts[0]), parts[1]
    except ValueError:
        return None


class SecretProviderResolutionError(Exception):
    def __init__(self, source: SecretSource, provider: str, message: str):
        self.source = source
        self.provider = provider
        super().__init__(message)


class SecretRefResolutionError(Exception):
    def __init__(self, source: SecretSource, provider: str, ref_id: str, message: str):
        self.source = source
        self.provider = provider
        self.ref_id = ref_id
        super().__init__(message)


class SecretResolver:
    def __init__(
        self,
        providers: dict[SecretSource, SecretsProvider] | dict[str, SecretsProvider] | None = None,
        max_provider_concurrency: int = DEFAULT_PROVIDER_CONCURRENCY,
        max_refs_per_provider: int = DEFAULT_MAX_REFS_PER_PROVIDER,
    ):
        self._providers: dict[str, SecretsProvider] = {}
        if providers:
            for key, provider in providers.items():
                if isinstance(key, SecretSource):
                    self._providers[_provider_key(key)] = provider
                else:
                    self._providers[key] = provider
        else:
            self._providers = {
                _provider_key(SecretSource.ENV): EnvProvider(),
                _provider_key(SecretSource.FILE): FileProvider(),
                _provider_key(SecretSource.EXEC): ExecProvider(),
            }
        self._max_provider_concurrency = max_provider_concurrency
        self._max_refs_per_provider = max_refs_per_provider

    def register_provider(
        self,
        source: SecretSource,
        provider: SecretsProvider,
        alias: str | None = None,
    ) -> None:
        self._providers[_provider_key(source, alias)] = provider

    async def resolve(self, config: dict[str, Any], path: str = "") -> SecretResolveResult:
        result = SecretResolveResult(resolved={}, issues=[], warnings=[])
        await self._walk(config, result.resolved, path, result)
        return result

    async def resolve_secret_ref_values(self, refs: list[SecretRef]) -> dict[str, str | None]:
        if not refs:
            return {}

        unique_refs: dict[str, SecretRef] = {}
        for ref in refs:
            ref_id = ref.ref.strip()
            if not ref_id:
                raise ValueError("Secret reference id is empty.")
            if ref.source == SecretSource.EXEC and not is_valid_exec_secret_ref_id(ref_id):
                raise ValueError(
                    f"Invalid exec secret ref id '{ref_id}': must match /^[A-Za-z0-9][A-Za-z0-9._:/-]{{0,255}}$/"
                )
            normalized = SecretRef(source=ref.source, ref=ref_id, provider=ref.provider)
            unique_refs[secret_ref_key(normalized)] = normalized

        grouped: dict[str, list[SecretRef]] = defaultdict(list)
        for ref in unique_refs.values():
            provider_alias = ref.provider or DEFAULT_SECRET_PROVIDER_ALIAS
            group_key = _provider_key(ref.source, provider_alias)
            grouped[group_key].append(ref)

        for group_key, group_refs in grouped.items():
            if len(group_refs) > self._max_refs_per_provider:
                raise SecretProviderResolutionError(
                    source=group_refs[0].source,
                    provider=group_refs[0].provider or DEFAULT_SECRET_PROVIDER_ALIAS,
                    message=f"Provider exceeded maxRefsPerProvider ({self._max_refs_per_provider}).",
                )

        semaphore = asyncio.Semaphore(self._max_provider_concurrency)

        async def resolve_group(group_refs: list[SecretRef]) -> dict[str, str | None]:
            async with semaphore:
                first = group_refs[0]
                provider = self._providers.get(_provider_key(first.source, first.provider))
                if provider is None:
                    raise SecretProviderResolutionError(
                        source=first.source,
                        provider=first.provider or DEFAULT_SECRET_PROVIDER_ALIAS,
                        message=(
                            f"No provider registered for source '{first.source.value}'"
                            f" with alias '{first.provider or DEFAULT_SECRET_PROVIDER_ALIAS}'"
                        ),
                    )
                batch_result = await provider.resolve_batch(group_refs)
                return {secret_ref_key(ref): batch_result.get(ref.ref) for ref in group_refs}

        tasks = [resolve_group(g) for g in grouped.values()]
        results = await asyncio.gather(*tasks, return_exceptions=True)

        resolved: dict[str, str | None] = {}
        errors: list[Exception] = []
        for r in results:
            if isinstance(r, Exception):
                errors.append(r)
            else:
                resolved.update(r)

        if errors:
            if len(errors) == 1:
                raise errors[0]
            raise ExceptionGroup("Secret resolution failed for one or more providers", errors)
        return resolved

    async def resolve_secret_ref_value(self, ref: SecretRef) -> str | None:
        ref_id = ref.ref.strip()
        if not ref_id:
            raise ValueError("Secret reference id is empty.")
        normalized = SecretRef(source=ref.source, ref=ref_id, provider=ref.provider)
        resolved = await self.resolve_secret_ref_values([normalized])
        return resolved.get(secret_ref_key(normalized))

    async def _walk(
        self,
        src: Any,
        dst: dict,
        path: str,
        result: SecretResolveResult,
    ) -> None:
        if not isinstance(src, dict):
            return

        for key, value in src.items():
            current_path = f"{path}.{key}" if path else key

            if is_secret_ref(value):
                resolved = await self._resolve_ref(value, current_path, result)
                dst[key] = resolved if resolved is not None else ""
            elif isinstance(value, dict):
                dst[key] = {}
                await self._walk(value, dst[key], current_path, result)
            elif isinstance(value, list):
                dst[key] = await self._walk_list(value, current_path, result)
            else:
                dst[key] = value

    async def _walk_list(
        self,
        src: list,
        path: str,
        result: SecretResolveResult,
    ) -> list:
        resolved_list = []
        for i, item in enumerate(src):
            item_path = f"{path}[{i}]"
            if is_secret_ref(item):
                resolved = await self._resolve_ref(item, item_path, result)
                resolved_list.append(resolved if resolved is not None else "")
            elif isinstance(item, dict):
                item_resolved: dict = {}
                await self._walk(item, item_resolved, item_path, result)
                resolved_list.append(item_resolved)
            elif isinstance(item, list):
                resolved_list.append(await self._walk_list(item, item_path, result))
            else:
                resolved_list.append(item)
        return resolved_list

    async def _resolve_ref(
        self,
        value: dict,
        path: str,
        result: SecretResolveResult,
    ) -> str | None:
        ref = parse_secret_ref(value)
        if ref is None:
            issue = SecretIssue(path=path, message="Invalid $secret format", severity="error")
            result.issues.append(issue)
            return None

        validation_error = validate_ref_id(ref.source, ref.ref)
        if validation_error:
            result.issues.append(SecretIssue(path=path, message=validation_error, ref=ref))
            return None

        provider = self._providers.get(_provider_key(ref.source, ref.provider))
        if provider is None:
            result.issues.append(
                SecretIssue(
                    path=path,
                    message=(
                        f"No provider registered for source '{ref.source.value}'"
                        f" with alias '{ref.provider or DEFAULT_SECRET_PROVIDER_ALIAS}'"
                    ),
                    ref=ref,
                )
            )
            return None

        try:
            resolved = await provider.resolve(ref)
        except asyncio.CancelledError:
            raise
        except Exception as e:
            result.issues.append(SecretIssue(path=path, message=f"Resolution failed: {e}", ref=ref))
            return None

        if resolved is None:
            result.warnings.append(
                SecretIssue(
                    path=path,
                    message=f"Secret not found: {ref.source.value}:{ref.ref}",
                    ref=ref,
                    severity="warning",
                )
            )
        return resolved


async def resolve_secrets(
    config: dict[str, Any],
    providers: dict[SecretSource, SecretsProvider] | None = None,
) -> SecretResolveResult:
    resolver = SecretResolver(providers)
    return await resolver.resolve(config)


def create_exec_provider(
    command: str,
    args: list[str] | None = None,
    timeout_ms: int = 5000,
    max_output_bytes: int = 1024 * 1024,
    pass_env: list[str] | None = None,
    extra_env: dict[str, str] | None = None,
    trusted_dirs: set[str] | None = None,
) -> ExecProvider:
    return ExecProvider(
        command=command,
        args=args or [],
        trusted_dirs=trusted_dirs or set(),
        timeout_ms=timeout_ms,
        max_output_bytes=max_output_bytes,
        pass_env=pass_env or [],
        extra_env=extra_env or {},
    )


def create_resolver_with_exec(
    command: str,
    args: list[str] | None = None,
    alias: str = "default",
    timeout_ms: int = 5000,
    max_output_bytes: int = 1024 * 1024,
    pass_env: list[str] | None = None,
    extra_env: dict[str, str] | None = None,
    env_allowlist: set[str] | None = None,
    file_base_dir: str | None = None,
    max_provider_concurrency: int = DEFAULT_PROVIDER_CONCURRENCY,
    max_refs_per_provider: int = DEFAULT_MAX_REFS_PER_PROVIDER,
) -> SecretResolver:
    provider = create_exec_provider(
        command=command,
        args=args,
        timeout_ms=timeout_ms,
        max_output_bytes=max_output_bytes,
        pass_env=pass_env,
        extra_env=extra_env,
    )
    env_provider = EnvProvider(allowlist=env_allowlist) if env_allowlist else EnvProvider()
    file_provider = FileProvider(base_dir=file_base_dir) if file_base_dir else FileProvider()
    resolver = SecretResolver(
        max_provider_concurrency=max_provider_concurrency,
        max_refs_per_provider=max_refs_per_provider,
    )
    resolver.register_provider(SecretSource.ENV, env_provider, alias=None)
    resolver.register_provider(SecretSource.FILE, file_provider, alias=None)
    resolver.register_provider(SecretSource.EXEC, provider, alias=alias)
    return resolver