package db

import (
	"database/sql"
	"fmt"
	"strings"
)

// ClearanceEvent is one clearance elevation audit row.
type ClearanceEvent struct {
	ID        int64  `json:"id"`
	AgentID   string `json:"agent_id"`
	FromLevel int    `json:"from_level"`
	ToLevel   int    `json:"to_level"`
	Reason    string `json:"reason"`
	Source    string `json:"source"`
	Timestamp string `json:"ts"`
}

func (d *Database) ensureClearanceEventsTable() error {
	_, err := d.Exec(`CREATE TABLE IF NOT EXISTS clearance_events (
		id INTEGER PRIMARY KEY AUTOINCREMENT,
		agent_id TEXT NOT NULL,
		from_level INTEGER NOT NULL DEFAULT 0,
		to_level INTEGER NOT NULL DEFAULT 0,
		reason TEXT NOT NULL DEFAULT '',
		source TEXT NOT NULL DEFAULT '',
		ts DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
	)`)
	if err != nil {
		return err
	}
	_, _ = d.Exec(`CREATE INDEX IF NOT EXISTS idx_clearance_events_agent ON clearance_events(agent_id)`)
	_, _ = d.Exec(`CREATE INDEX IF NOT EXISTS idx_clearance_events_ts ON clearance_events(ts)`)
	return nil
}

// InsertClearanceEvent logs a clearance elevation.
func (d *Database) InsertClearanceEvent(agentID string, fromLevel, toLevel int, reason, source string) error {
	if d == nil {
		return nil
	}
	if err := d.ensureClearanceEventsTable(); err != nil {
		return err
	}
	_, err := d.Exec(
		`INSERT INTO clearance_events (agent_id, from_level, to_level, reason, source) VALUES (?, ?, ?, ?, ?)`,
		agentID, fromLevel, toLevel, reason, source,
	)
	return err
}

// ListClearanceEvents returns recent clearance events for an agent (or fleet-wide when agentID empty).
func (d *Database) ListClearanceEvents(agentID string, limit int) ([]ClearanceEvent, error) {
	if d == nil {
		return nil, nil
	}
	if err := d.ensureClearanceEventsTable(); err != nil {
		return nil, err
	}
	if limit <= 0 {
		limit = 50
	}
	if limit > 500 {
		limit = 500
	}

	var rows *sql.Rows
	var err error
	agentID = strings.TrimSpace(agentID)
	if agentID != "" {
		rows, err = d.Query(
			`SELECT id, agent_id, from_level, to_level, reason, source, ts
			 FROM clearance_events WHERE agent_id = ? ORDER BY id DESC LIMIT ?`,
			agentID, limit,
		)
	} else {
		rows, err = d.Query(
			`SELECT id, agent_id, from_level, to_level, reason, source, ts
			 FROM clearance_events ORDER BY id DESC LIMIT ?`,
			limit,
		)
	}
	if err != nil {
		return nil, fmt.Errorf("list clearance events: %w", err)
	}
	defer rows.Close()

	out := make([]ClearanceEvent, 0, limit)
	for rows.Next() {
		var rec ClearanceEvent
		var ts string
		if err := rows.Scan(&rec.ID, &rec.AgentID, &rec.FromLevel, &rec.ToLevel, &rec.Reason, &rec.Source, &ts); err != nil {
			return nil, err
		}
		rec.Timestamp = ts
		out = append(out, rec)
	}
	return out, rows.Err()
}