"""Multi-provider resource merging with conflict resolution.

Merges resources from multiple scan profiles into a unified inventory,
resolving naming conflicts by prefixing with the provider identifier.
"""

from dataclasses import replace
from collections import defaultdict

from iac_reverse.models import DiscoveredResource, ScanResult


class ResourceMerger:
    """Merges resources from multiple ScanResult objects into a unified list.

    When resources from different providers share the same name, the merger
    resolves the conflict by prefixing each conflicting resource's name with
    its provider identifier (e.g., "kubernetes_nginx", "docker_swarm_nginx").

    Provider-specific attributes are preserved unchanged.
    """

    def merge(self, scan_results: list[ScanResult]) -> list[DiscoveredResource]:
        """Merge resources from multiple scan results into a unified list.

        Args:
            scan_results: List of ScanResult objects, one per provider/scan profile.

        Returns:
            A unified list of DiscoveredResource with naming conflicts resolved
            by prefixing conflicting names with the provider identifier.
        """
        # Collect all resources from all scan results
        all_resources: list[DiscoveredResource] = []
        for result in scan_results:
            all_resources.extend(result.resources)

        # Group resources by name to detect conflicts
        resources_by_name: dict[str, list[DiscoveredResource]] = defaultdict(list)
        for resource in all_resources:
            resources_by_name[resource.name].append(resource)

        # Identify conflicting names: same name from different providers
        conflicting_names: set[str] = set()
        for name, resources in resources_by_name.items():
            providers = {r.provider for r in resources}
            if len(providers) > 1:
                conflicting_names.add(name)

        # Build the merged list, resolving conflicts
        merged: list[DiscoveredResource] = []
        for resource in all_resources:
            if resource.name in conflicting_names:
                prefixed_name = f"{resource.provider.value}_{resource.name}"
                merged.append(replace(resource, name=prefixed_name))
            else:
                merged.append(resource)

        return merged