package master

import (
	"database/sql"
	"fmt"
	"sort"

	"git.wntrmute.dev/mc/mcp/internal/masterdb"
)

// PickNode selects the best worker node for a new service deployment.
// Algorithm: fewest placed services, ties broken alphabetically.
func PickNode(db *sql.DB) (string, error) {
	workers, err := masterdb.ListWorkerNodes(db)
	if err != nil {
		return "", fmt.Errorf("list workers: %w", err)
	}
	if len(workers) == 0 {
		return "", fmt.Errorf("no worker nodes available")
	}

	counts, err := masterdb.CountPlacementsPerNode(db)
	if err != nil {
		return "", fmt.Errorf("count placements: %w", err)
	}

	// Sort: fewest placements first, then alphabetically.
	sort.Slice(workers, func(i, j int) bool {
		ci := counts[workers[i].Name]
		cj := counts[workers[j].Name]
		if ci != cj {
			return ci < cj
		}
		return workers[i].Name < workers[j].Name
	})

	return workers[0].Name, nil
}

// FindMasterNode returns the name of the node with role "master".
func FindMasterNode(db *sql.DB) (string, error) {
	nodes, err := masterdb.ListNodes(db)
	if err != nil {
		return "", fmt.Errorf("list nodes: %w", err)
	}
	for _, n := range nodes {
		if n.Role == "master" {
			return n.Name, nil
		}
	}
	return "", fmt.Errorf("no master node found")
}

// FindEdgeNode returns the name of the first edge node.
func FindEdgeNode(db *sql.DB) (string, error) {
	edges, err := masterdb.ListEdgeNodes(db)
	if err != nil {
		return "", fmt.Errorf("list edge nodes: %w", err)
	}
	if len(edges) == 0 {
		return "", fmt.Errorf("no edge nodes available")
	}
	return edges[0].Name, nil
}