package hostbox

import (
	"bytes"
	"context"
	"database/sql"
	"encoding/json"
	"io"
	"net/url"
	"os"
	"path/filepath"
)

// GenerationLaunches includes hosts absent from the reservation directory.
// Only the checked local journal is eligible; an agent list is not a census.
func (j *LaunchJournal) GenerationLaunches(ctx context.Context) ([]LaunchInventory, 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 identity, body FROM launches ORDER BY identity")
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []LaunchInventory
	for rows.Next() {
		var key string
		var body []byte
		if err := rows.Scan(&key, &body); err != nil {
			return nil, err
		}
		if len(body) > 1<<20 || len(out) >= 8192 {
			return nil, ErrTypedInventory
		}
		var in LaunchInventory
		dec := json.NewDecoder(bytes.NewReader(body))
		dec.DisallowUnknownFields()
		if dec.Decode(&in) != nil || dec.Decode(new(any)) != io.EOF || !validLaunchOwner(in.Target) || launchKey(in.Target) != key || !in.Completed.Valid() || in.ControllerPID <= 0 || in.ProcessStart == "" {
			return nil, ErrTypedInventory
		}
		out = append(out, in)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	if err := journalIdentity(j.path, j.identity); err != nil {
		return nil, err
	}
	return out, nil
}

// OpenGenerationLaunchReader never creates a database or initializes its schema.
// Production callers must check root ownership of the database and sidecars.
func OpenGenerationLaunchReader(path string) (*LaunchJournal, error) {
	if !filepath.IsAbs(path) {
		return nil, ErrUnsupported
	}
	if err := checkJournalPath(path); err != nil {
		return nil, err
	}
	identity, err := os.Lstat(path)
	if err != nil {
		return nil, err
	}
	db, err := sql.Open("sqlite", "file:"+url.PathEscape(path)+"?mode=ro&_pragma=busy_timeout(5000)")
	if err != nil {
		return nil, err
	}
	db.SetMaxOpenConns(1)
	return &LaunchJournal{db: db, path: path, identity: identity}, nil
}