package hostbox

import (
	"bytes"
	"context"
	"encoding/json"
	"io"
	"path/filepath"
)

type GenerationPayload struct {
	Inventory StopInventory
	Revision  uint64
}

// GenerationPayloads reads both sides of the inventory/revision relation.
// An inner join would silently discard an obligation with a missing revision.
// The caller still has to bind these records to root installations and inspect
// kernel references; Complete in a stored payload cannot establish that alone.
func (j *LaunchJournal) GenerationPayloads(ctx context.Context) ([]GenerationPayload, error) {
	if j == nil || j.db == nil || j.remote != nil {
		return nil, ErrUnsupported
	}
	if err := journalIdentity(j.path, j.identity); err != nil {
		return nil, err
	}
	rows, err := journalExecutorFor(ctx, j.db).QueryContext(ctx, `
SELECT k.host,k.incarnation,k.stamp,i.body,v.revision
FROM (SELECT host,incarnation,stamp FROM stop_inventory
      UNION SELECT host,incarnation,stamp FROM journal_inventory_versions) k
LEFT JOIN stop_inventory i USING(host,incarnation,stamp)
LEFT JOIN journal_inventory_versions v USING(host,incarnation,stamp)
ORDER BY k.host,k.incarnation,k.stamp`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []GenerationPayload
	for rows.Next() {
		var host, incarnation string
		var stamp uint64
		var raw []byte
		var p GenerationPayload
		if err := rows.Scan(&host, &incarnation, &stamp, &raw, &p.Revision); err != nil {
			return nil, err
		}
		if len(raw) > 1<<20 || len(out) >= 8192 {
			return nil, ErrTypedInventory
		}
		dec := json.NewDecoder(bytes.NewReader(raw))
		dec.DisallowUnknownFields()
		if dec.Decode(&p.Inventory) != nil || dec.Decode(new(any)) != io.EOF {
			return nil, ErrTypedInventory
		}
		in := p.Inventory
		if !component(host) || incarnation == "" || stamp == 0 || p.Revision == 0 || in.Host != host || in.Incarnation != incarnation || in.InstallationStamp != stamp || !in.Complete || in.Box == "" || in.Enrollment == "" || in.DirectoryRevision == "" {
			return nil, ErrTypedInventory
		}
		ids := map[string]bool{}
		for _, e := range in.Entries {
			if !component(e.ArtifactID) || ids[e.ArtifactID] || !filepath.IsLocal(e.RelativePath) || e.Ownership == "" || (e.Materialization != "intended" && e.Materialization != "materialized") {
				return nil, ErrTypedInventory
			}
			ids[e.ArtifactID] = true
			switch e.Kind {
			case "route", "timer":
				if e.ManagedRoot != "registry" || e.RowIdentity == "" || e.Device != 0 || e.Inode != 0 || e.Type != 0 {
					return nil, ErrTypedInventory
				}
			case "path":
				if e.ManagedRoot != "data" || e.RowIdentity != "" || (e.Materialization == "materialized" && (e.Device == 0 || e.Inode == 0 || e.Type == 0)) {
					return nil, ErrTypedInventory
				}
			default:
				return nil, ErrTypedInventory
			}
		}
		out = append(out, p)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	if err := journalIdentity(j.path, j.identity); err != nil {
		return nil, err
	}
	return out, nil
}