"""Smart merge strategy for .dss imports with conflict detection"""

import hashlib
from datetime import datetime
from typing import Dict, Any, List, Optional, Tuple, Literal
from dataclasses import dataclass
from enum import Enum

from .security import TimestampConflictResolver
from ..models.project import Project
from ..models.theme import DesignToken
from ..models.component import Component
from dss.storage.json_store import Projects, Components, Tokens


MergeStrategy = Literal["overwrite", "keep_local", "fork", "skip"]


class ConflictResolutionMode(str, Enum):
    """How to handle conflicts during merge"""

    OVERWRITE = "overwrite"  # Import wins
    KEEP_LOCAL = "keep_local"  # Local wins
    FORK = "fork"  # Create duplicate with new UUID
    MANUAL = "manual"  # Require user decision


@dataclass
class ConflictItem:
    """Detected conflict"""

    uuid: str
    entity_type: str  # token, component, theme
    entity_name: str
    local_updated_at: datetime
    imported_updated_at: datetime
    local_hash: str
    imported_hash: str
    is_modified_both: bool  # True if changed in both places

    @property
    def local_is_newer(self) -> bool:
        """Is local version newer?"""
        return self.local_updated_at > self.imported_updated_at

    @property
    def imported_is_newer(self) -> bool:
        """Is imported version newer?"""
        return self.imported_updated_at > self.local_updated_at

    @property
    def is_identical(self) -> bool:
        """Are both versions identical?"""
        return self.local_hash == self.imported_hash

    def get_safe_recommendation(self, allow_drift_detection: bool = True) -> Tuple[str, Optional[str]]:
        """Get safe conflict resolution recommendation with clock skew detection.

        Uses TimestampConflictResolver to safely determine winner, accounting
        for possible clock drift between systems.

        Args:
            allow_drift_detection: If True, warn about possible clock skew

        Returns:
            Tuple of (recommended_winner: 'local'|'imported'|'unknown', warning: str|None)
        """
        resolver = TimestampConflictResolver()
        return resolver.resolve_conflict(
            self.local_updated_at,
            self.imported_updated_at,
            allow_drift_detection=allow_drift_detection,
        )


@dataclass
class MergeAnalysis:
    """Analysis of merge operation"""

    new_items: Dict[str, List[str]]  # type -> [names]
    updated_items: Dict[str, List[str]]  # type -> [names]
    conflicted_items: List[ConflictItem]
    total_changes: int

    @property
    def has_conflicts(self) -> bool:
        """Are there conflicts?"""
        return len(self.conflicted_items) > 0


class UUIDHashMap:
    """Maps UUIDs to content hashes for detecting changes"""

    def __init__(self):
        self.hashes: Dict[str, str] = {}

    @staticmethod
    def hash_token(token: DesignToken) -> str:
        """Generate stable hash of token content (excludes UUID, timestamps)"""
        content = f"{token.name}:{token.value}:{token.type}:{token.category}:{token.description}:{token.source}:{token.deprecated}"
        return hashlib.sha256(content.encode()).hexdigest()

    @staticmethod
    def hash_component(component: Component) -> str:
        """Generate stable hash of component content"""
        import json

        content = json.dumps(
            {
                "name": component.name,
                "source": component.source,
                "description": component.description,
                "variants": component.variants,
                "props": component.props,
                "dependencies": sorted(component.dependencies),
            },
            sort_keys=True,
        )
        return hashlib.sha256(content.encode()).hexdigest()

    def add_token(self, token: DesignToken):
        """Add token to hash map"""
        self.hashes[token.uuid] = self.hash_token(token)

    def add_component(self, component: Component):
        """Add component to hash map"""
        self.hashes[component.uuid] = self.hash_component(component)

    def get(self, uuid: str) -> Optional[str]:
        """Get hash for UUID"""
        return self.hashes.get(uuid)


class SmartMerger:
    """Intelligent merge strategy for archives"""

    def __init__(self, local_project: Project, imported_project: Project):
        self.local_project = local_project
        self.imported_project = imported_project

    def analyze_merge(self) -> MergeAnalysis:
        """
        Analyze what would happen in a merge without modifying anything

        Returns:
            MergeAnalysis with new, updated, and conflicted items
        """
        new_items: Dict[str, List[str]] = {
            "tokens": [],
            "components": [],
            "themes": [],
        }
        updated_items: Dict[str, List[str]] = {
            "tokens": [],
            "components": [],
            "themes": [],
        }
        conflicts = []

        # Build local UUID maps
        local_token_uuids = {t.uuid: t for t in self.local_project.theme.tokens.values()}
        local_component_uuids = {c.uuid: c for c in self.local_project.components}

        # Check imported tokens
        for token_name, imported_token in self.imported_project.theme.tokens.items():
            if imported_token.uuid not in local_token_uuids:
                new_items["tokens"].append(token_name)
            else:
                local_token = local_token_uuids[imported_token.uuid]
                if local_token != imported_token:
                    # Detect conflict
                    conflict = self._detect_token_conflict(
                        imported_token.uuid,
                        local_token,
                        imported_token,
                    )
                    if conflict:
                        conflicts.append(conflict)
                    else:
                        updated_items["tokens"].append(token_name)

        # Check imported components
        for imported_comp in self.imported_project.components:
            if imported_comp.uuid not in local_component_uuids:
                new_items["components"].append(imported_comp.name)
            else:
                local_comp = local_component_uuids[imported_comp.uuid]
                if local_comp != imported_comp:
                    conflict = self._detect_component_conflict(
                        imported_comp.uuid,
                        local_comp,
                        imported_comp,
                    )
                    if conflict:
                        conflicts.append(conflict)
                    else:
                        updated_items["components"].append(imported_comp.name)

        total_changes = (
            len(new_items["tokens"])
            + len(new_items["components"])
            + len(updated_items["tokens"])
            + len(updated_items["components"])
            + len(conflicts)
        )

        return MergeAnalysis(
            new_items=new_items,
            updated_items=updated_items,
            conflicted_items=conflicts,
            total_changes=total_changes,
        )

    def merge_with_strategy(
        self,
        conflict_handler: ConflictResolutionMode = ConflictResolutionMode.OVERWRITE,
    ) -> Project:
        """
        Perform merge with specified conflict strategy

        Args:
            conflict_handler: How to handle conflicts

        Returns:
            Merged project
        """
        analysis = self.analyze_merge()

        # Create copy of local project
        merged_project = self.local_project.model_copy(deep=True)

        # Apply new tokens
        for token_name in analysis.new_items["tokens"]:
            if token_name in self.imported_project.theme.tokens:
                imported_token = self.imported_project.theme.tokens[token_name]
                merged_project.theme.tokens[token_name] = imported_token.model_copy()

        # Apply updated tokens
        for token_name in analysis.updated_items["tokens"]:
            if token_name in self.imported_project.theme.tokens:
                imported_token = self.imported_project.theme.tokens[token_name]
                merged_project.theme.tokens[token_name] = imported_token.model_copy()

        # Apply new components
        for comp in self.imported_project.components:
            if not any(c.uuid == comp.uuid for c in merged_project.components):
                merged_project.components.append(comp.model_copy())

        # Apply updated components
        for comp in self.imported_project.components:
            for i, local_comp in enumerate(merged_project.components):
                if local_comp.uuid == comp.uuid:
                    merged_project.components[i] = comp.model_copy()
                    break

        # Handle conflicts based on strategy
        for conflict in analysis.conflicted_items:
            self._resolve_conflict(
                merged_project,
                conflict,
                conflict_handler,
            )

        return merged_project

    def _detect_token_conflict(
        self,
        token_uuid: str,
        local_token: DesignToken,
        imported_token: DesignToken,
    ) -> Optional[ConflictItem]:
        """Check if token versions conflict"""
        local_hash = UUIDHashMap.hash_token(local_token)
        imported_hash = UUIDHashMap.hash_token(imported_token)

        # No conflict if identical
        if local_hash == imported_hash:
            return None

        # Conflict detected
        return ConflictItem(
            uuid=token_uuid,
            entity_type="token",
            entity_name=local_token.name,
            local_updated_at=local_token.updated_at,
            imported_updated_at=imported_token.updated_at,
            local_hash=local_hash,
            imported_hash=imported_hash,
            is_modified_both=True,
        )

    def _detect_component_conflict(
        self,
        comp_uuid: str,
        local_comp: Component,
        imported_comp: Component,
    ) -> Optional[ConflictItem]:
        """Check if component versions conflict"""
        local_hash = UUIDHashMap.hash_component(local_comp)
        imported_hash = UUIDHashMap.hash_component(imported_comp)

        # No conflict if identical
        if local_hash == imported_hash:
            return None

        # Conflict detected
        return ConflictItem(
            uuid=comp_uuid,
            entity_type="component",
            entity_name=local_comp.name,
            local_updated_at=local_comp.updated_at if hasattr(local_comp, 'updated_at') else datetime.utcnow(),
            imported_updated_at=imported_comp.updated_at if hasattr(imported_comp, 'updated_at') else datetime.utcnow(),
            local_hash=local_hash,
            imported_hash=imported_hash,
            is_modified_both=True,
        )

    def _resolve_conflict(
        self,
        project: Project,
        conflict: ConflictItem,
        strategy: ConflictResolutionMode,
    ):
        """Apply conflict resolution strategy"""
        if strategy == ConflictResolutionMode.OVERWRITE:
            # Import wins - already applied
            pass
        elif strategy == ConflictResolutionMode.KEEP_LOCAL:
            # Undo the import
            if conflict.entity_type == "token":
                # Find and restore local token
                local_token = next(
                    (t for t in self.local_project.theme.tokens.values() if t.uuid == conflict.uuid),
                    None,
                )
                if local_token:
                    project.theme.tokens[local_token.name] = local_token.model_copy()

            elif conflict.entity_type == "component":
                local_comp = next(
                    (c for c in self.local_project.components if c.uuid == conflict.uuid),
                    None,
                )
                if local_comp:
                    for i, comp in enumerate(project.components):
                        if comp.uuid == conflict.uuid:
                            project.components[i] = local_comp.model_copy()
                            break

        elif strategy == ConflictResolutionMode.FORK:
            # Create new item with new UUID
            from uuid import uuid4

            if conflict.entity_type == "token":
                imported_token = next(
                    (t for t in self.imported_project.theme.tokens.values() if t.uuid == conflict.uuid),
                    None,
                )
                if imported_token:
                    forked = imported_token.model_copy()
                    forked.uuid = str(uuid4())
                    project.theme.tokens[f"{imported_token.name}_imported"] = forked

            elif conflict.entity_type == "component":
                imported_comp = next(
                    (c for c in self.imported_project.components if c.uuid == conflict.uuid),
                    None,
                )
                if imported_comp:
                    forked = imported_comp.model_copy()
                    forked.uuid = str(uuid4())
                    forked.name = f"{imported_comp.name}_imported"
                    project.components.append(forked)


# Export
__all__ = [
    "SmartMerger",
    "ConflictResolutionMode",
    "ConflictItem",
    "MergeAnalysis",
    "UUIDHashMap",
]