package db

import (
	"fmt"
	"strings"

	"crypto-miner-server/internal/models"
)

// AgentListFilter holds optional filters for paginated agent queries.
type AgentListFilter struct {
	Limit  int    // 0 = no limit (return all matching rows)
	Offset int
	Status string // "online", "offline", or "" for any
	Subnet string // e.g. "10.0.0.x" — matched against agents.ip prefix
}

// subnetToIPPrefix converts UI subnet labels to SQL LIKE patterns.
func subnetToIPPrefix(subnet string) string {
	subnet = strings.TrimSpace(subnet)
	if subnet == "" {
		return ""
	}
	if strings.HasSuffix(subnet, ".x") {
		return strings.TrimSuffix(subnet, ".x") + ".%"
	}
	if strings.HasSuffix(subnet, "%") {
		return subnet
	}
	parts := strings.Split(subnet, ".")
	if len(parts) >= 3 {
		return fmt.Sprintf("%s.%s.%s.%%", parts[0], parts[1], parts[2])
	}
	return subnet + "%"
}

func (d *Database) agentListWhere(f AgentListFilter) (clause string, args []interface{}) {
	var where []string
	if f.Status != "" {
		where = append(where, "status = ?")
		args = append(args, f.Status)
	}
	if prefix := subnetToIPPrefix(f.Subnet); prefix != "" {
		where = append(where, "ip LIKE ?")
		args = append(args, prefix)
	}
	if len(where) == 0 {
		return "", nil
	}
	return " WHERE " + strings.Join(where, " AND "), args
}

// ListAgentsFiltered returns agents matching optional status/subnet filters.
// When Limit > 0, results are paginated with Offset.
func (d *Database) ListAgentsFiltered(f AgentListFilter) ([]*models.Agent, error) {
	where, args := d.agentListWhere(f)
	query := `SELECT ` + agentSelectCols + ` FROM agents` + where + ` ORDER BY last_seen DESC`
	if f.Limit > 0 {
		query += ` LIMIT ? OFFSET ?`
		args = append(args, f.Limit, f.Offset)
	}
	rows, err := d.Query(query, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var agents []*models.Agent
	for rows.Next() {
		a, err := d.scanAgent(rows)
		if err != nil {
			return nil, err
		}
		agents = append(agents, a)
	}
	return agents, rows.Err()
}

// CountAgentsFiltered returns the number of agents matching filter criteria (ignores Limit/Offset).
func (d *Database) CountAgentsFiltered(f AgentListFilter) (int, error) {
	where, args := d.agentListWhere(f)
	var n int
	err := d.QueryRow(`SELECT COUNT(*) FROM agents`+where, args...).Scan(&n)
	return n, err
}