package platform

import (
	"database/sql"
	"encoding/json"
	"net/http"
	"sort"
)

// Deletion or kind/ownership changes revoke active steps in the same snapshot
// transaction. Recreating an identical node ID later cannot revive that step.
func invalidateCanvasAITargets(r *http.Request, tx *sql.Tx, project, workspace, board string, before, after json.RawMessage) error {
	old, next := canvasNodeData(before), canvasNodeData(after)
	removed := []string{}
	for node, data := range old {
		if next[node] == nil || next[node]["kind"] != data["kind"] {
			removed = append(removed, node)
		}
	}
	sort.Strings(removed)
	for _, node := range removed {
		rows, err := tx.QueryContext(r.Context(), `SELECT DISTINCT run_id::text FROM canvas_ai_steps WHERE project=$1 AND workspace_id=$2 AND board_id=$3 AND node_id=$4 AND status IN('queued','running') ORDER BY run_id::text`, project, workspace, board, node)
		if err != nil {
			return err
		}
		runs := []string{}
		for rows.Next() {
			var id string
			if err = rows.Scan(&id); err != nil {
				break
			}
			runs = append(runs, id)
		}
		if err == nil {
			err = rows.Err()
		}
		rows.Close()
		if err != nil {
			return err
		}
		for _, run := range runs {
			var rawPlan json.RawMessage
			err = tx.QueryRowContext(r.Context(), `SELECT plan FROM canvas_ai_runs WHERE project=$1 AND workspace_id=$2 AND id=$3 FOR UPDATE`, project, workspace, run).Scan(&rawPlan)
			if err != nil {
				return err
			}
			var step string
			err = tx.QueryRowContext(r.Context(), `UPDATE canvas_ai_steps SET status='cancelled',error_code='target_removed',completed_at=now() WHERE project=$1 AND workspace_id=$2 AND run_id=$3 AND board_id=$4 AND node_id=$5 AND status IN('queued','running') RETURNING id`, project, workspace, run, board, node).Scan(&step)
			if err == sql.ErrNoRows {
				continue
			}
			if err != nil {
				return err
			}
			if err = appendAIEvent(r.Context(), tx, project, workspace, run, "step.cancelled", response{"step_id": step, "board_id": board, "node_id": node, "error": "target_removed"}); err != nil {
				return err
			}
			var plan canvasAIPlan
			if err = json.Unmarshal(rawPlan, &plan); err != nil {
				return err
			}
			for _, edge := range plan.Edges {
				if edge.Target == step {
					if err = appendAIEvent(r.Context(), tx, project, workspace, run, "edge.skipped", response{"logical_edge_id": edge.ID, "status": "skipped"}); err != nil {
						return err
					}
				}
			}
		}
	}
	return nil
}

func invalidateCanvasAISubtree(r *http.Request, tx *sql.Tx, project, workspace, child string) error {
	rows, err := tx.QueryContext(r.Context(), `WITH RECURSIVE descendants(id,depth) AS(SELECT $3::uuid,0 UNION ALL SELECT s.child_board_id,d.depth+1 FROM descendants d JOIN canvas_subgraphs s ON s.project=$1 AND s.workspace_id=$2 AND s.parent_board_id=d.id AND s.archived_at IS NULL WHERE d.depth<8) SELECT m.id::text,COALESCE(m.canvas_document,'{"nodes":[]}'::jsonb) FROM descendants d JOIN materials m ON m.project=$1 AND m.workspace_id=$2 AND m.id=d.id ORDER BY m.id`, project, workspace, child)
	if err != nil {
		return err
	}
	snapshots := []canvasSnapshot{}
	for rows.Next() {
		var snapshot canvasSnapshot
		if err = rows.Scan(&snapshot.BoardID, &snapshot.Document); err != nil {
			break
		}
		snapshots = append(snapshots, snapshot)
	}
	if err == nil {
		err = rows.Err()
	}
	rows.Close()
	if err != nil {
		return err
	}
	for _, snapshot := range snapshots {
		if err = invalidateCanvasAITargets(r, tx, project, workspace, snapshot.BoardID, snapshot.Document, json.RawMessage(`{"nodes":[]}`)); err != nil {
			return err
		}
	}
	return nil
}