package store

import (
	"bytes"
	"crypto/sha256"
	"database/sql"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"strings"

	"git.ipao.vip/rogee/go-sip/internal/configread"
)

// CurrentStore is the authority for the new numeric-tenant task model. It
// deliberately refuses an old database instead of clearing or replaying data
// whose owner/message identity cannot be proved safe to convert.
type CurrentStore struct{ db *sql.DB }

const currentSchema = `
CREATE TABLE IF NOT EXISTS dispatcher_state (
    dispatcher_id TEXT PRIMARY KEY,
    discovery_ready INTEGER NOT NULL DEFAULT 0 CHECK(discovery_ready IN (0,1)),
    applied_sip_revision INTEGER NOT NULL DEFAULT 0 CHECK(applied_sip_revision >= 0),
    pending_sip_revision INTEGER NOT NULL DEFAULT 0 CHECK(pending_sip_revision >= 0)
);
CREATE TABLE IF NOT EXISTS dispatcher_tasks (
    dispatcher_id TEXT NOT NULL,
    tenant_id INTEGER NOT NULL CHECK(tenant_id > 0),
    task_id TEXT NOT NULL,
    task_revision INTEGER NOT NULL CHECK(task_revision > 0),
    status TEXT NOT NULL CHECK(status IN ('running','paused','stopped')),
    control_state TEXT NOT NULL DEFAULT '' CHECK(control_state IN ('','pausing','paused','stopping','stopped','resuming')),
    present INTEGER NOT NULL DEFAULT 1 CHECK(present IN (0,1)),
    PRIMARY KEY(dispatcher_id,tenant_id,task_id)
);
CREATE TABLE IF NOT EXISTS dispatcher_configs (
    dispatcher_id TEXT NOT NULL,
    tenant_id INTEGER NOT NULL CHECK(tenant_id > 0),
    task_id TEXT NOT NULL,
    task_revision INTEGER NOT NULL CHECK(task_revision > 0),
    sip_revision INTEGER NOT NULL CHECK(sip_revision > 0),
    quota_revision INTEGER NOT NULL CHECK(quota_revision > 0),
    content_sha256 TEXT NOT NULL,
    snapshot_json BLOB NOT NULL,
    PRIMARY KEY(dispatcher_id,tenant_id,task_id)
);
CREATE TABLE IF NOT EXISTS dispatcher_inbox (
    dispatcher_id TEXT NOT NULL,
    event_id TEXT NOT NULL,
    tenant_id INTEGER NOT NULL CHECK(tenant_id > 0),
    task_id TEXT NOT NULL,
    callee TEXT NOT NULL,
    issued_at TEXT NOT NULL,
    status TEXT NOT NULL CHECK(status IN ('pending','dispatching','dispatched','unknown','rejected','finished','suppressed')),
    selected_trunk_id TEXT,
    caller_id TEXT,
    dialed_callee TEXT,
    deadline TEXT,
    snapshot_json BLOB,
    PRIMARY KEY(dispatcher_id,event_id)
);
CREATE INDEX IF NOT EXISTS dispatcher_inbox_occupancy ON dispatcher_inbox(dispatcher_id,tenant_id,task_id,selected_trunk_id,status);
CREATE TABLE IF NOT EXISTS dispatcher_outbox (
    dispatcher_id TEXT NOT NULL,
    event_id TEXT NOT NULL,
    event_type TEXT NOT NULL,
    routing_key TEXT NOT NULL,
    body BLOB NOT NULL,
    confirmed INTEGER NOT NULL DEFAULT 0 CHECK(confirmed IN (0,1)),
    confirmed_at TEXT,
    PRIMARY KEY(dispatcher_id,event_id)
);
CREATE TABLE IF NOT EXISTS dispatcher_recordings (
    dispatcher_id TEXT NOT NULL,
    source_event_id TEXT NOT NULL,
    upload_id TEXT NOT NULL,
    recording_id TEXT NOT NULL,
    bucket TEXT NOT NULL,
    object_key TEXT NOT NULL,
    checksum_sha256 TEXT NOT NULL,
    size_bytes INTEGER NOT NULL CHECK(size_bytes > 0),
    format TEXT NOT NULL,
    channels INTEGER NOT NULL CHECK(channels > 0),
    sample_rate_hz INTEGER NOT NULL CHECK(sample_rate_hz > 0),
    duration_ms INTEGER NOT NULL CHECK(duration_ms >= 0),
    confirmed_at TEXT,
    PRIMARY KEY(dispatcher_id,source_event_id),
    UNIQUE(dispatcher_id,upload_id),
    UNIQUE(bucket,object_key),
    FOREIGN KEY(dispatcher_id,source_event_id) REFERENCES dispatcher_inbox(dispatcher_id,event_id)
);`

func OpenCurrent(path string) (_ *CurrentStore, err error) {
	if path == "" {
		return nil, errors.New("SQLite path is required")
	}
	db, err := sql.Open("sqlite", path)
	if err != nil {
		return nil, fmt.Errorf("open current SQLite: %w", err)
	}
	defer func() {
		if err != nil {
			db.Close()
		}
	}()
	db.SetMaxOpenConns(1)
	rows, err := db.Query(`SELECT name FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%'`)
	if err != nil {
		return nil, fmt.Errorf("inspect SQLite schema before writing: %w", err)
	}
	allowed := map[string]bool{"dispatcher_state": true, "dispatcher_tasks": true, "dispatcher_configs": true, "dispatcher_inbox": true, "dispatcher_outbox": true, "dispatcher_recordings": true}
	seen := make(map[string]bool, len(allowed))
	var unexpected []string
	for rows.Next() {
		var name string
		if err := rows.Scan(&name); err != nil {
			rows.Close()
			return nil, err
		}
		if !allowed[name] {
			unexpected = append(unexpected, name)
		} else {
			seen[name] = true
		}
	}
	err = rows.Err()
	rows.Close()
	if err != nil {
		return nil, fmt.Errorf("inspect SQLite tables: %w", err)
	}
	if len(unexpected) > 0 {
		return nil, fmt.Errorf("old or unknown SQLite tables %s: preserve database and reconcile manually before admission", strings.Join(unexpected, ","))
	}
	var version int
	if err := db.QueryRow(`PRAGMA user_version`).Scan(&version); err != nil {
		return nil, fmt.Errorf("inspect SQLite layout version before writing: %w", err)
	}
	if len(seen) == 0 {
		if version != 0 {
			return nil, fmt.Errorf("unknown SQLite layout version %d without tables: preserve database before admission", version)
		}
	} else {
		if len(seen) != len(allowed) || version != 2 {
			return nil, fmt.Errorf("existing SQLite layout is incomplete or obsolete (tables=%d, version=%d): preserve data before admission", len(seen), version)
		}
		var requiredColumns int
		if err := db.QueryRow(`SELECT COUNT(*) FROM pragma_table_info('dispatcher_state') WHERE name IN ('discovery_ready','applied_sip_revision','pending_sip_revision')`).Scan(&requiredColumns); err != nil {
			return nil, fmt.Errorf("inspect durable SIP state layout: %w", err)
		}
		if requiredColumns != 3 {
			return nil, errors.New("existing SQLite lacks durable SIP admission columns: preserve data before admission")
		}
		var recordingColumns int
		if err := db.QueryRow(`SELECT COUNT(*) FROM pragma_table_info('dispatcher_recordings') WHERE name IN ('dispatcher_id','source_event_id','upload_id','recording_id','bucket','object_key','checksum_sha256','size_bytes','format','channels','sample_rate_hz','duration_ms','confirmed_at')`).Scan(&recordingColumns); err != nil {
			return nil, fmt.Errorf("inspect original recording target layout: %w", err)
		}
		if recordingColumns != 13 {
			return nil, errors.New("existing SQLite lacks immutable recording target columns: preserve data before admission")
		}
	}
	for _, pragma := range []string{"PRAGMA busy_timeout=5000", "PRAGMA journal_mode=WAL", "PRAGMA synchronous=FULL", "PRAGMA foreign_keys=ON"} {
		if _, err := db.Exec(pragma); err != nil {
			return nil, fmt.Errorf("initialize SQLite %s: %w", pragma, err)
		}
	}
	if len(seen) == 0 {
		tx, err := db.Begin()
		if err != nil {
			return nil, err
		}
		defer tx.Rollback()
		if _, err := tx.Exec(currentSchema); err != nil {
			return nil, fmt.Errorf("create current SQLite schema: %w", err)
		}
		if _, err := tx.Exec(`PRAGMA user_version=2`); err != nil {
			return nil, fmt.Errorf("set current SQLite layout version: %w", err)
		}
		if err := tx.Commit(); err != nil {
			return nil, fmt.Errorf("commit current SQLite schema: %w", err)
		}
	} else if _, err := db.Exec(currentSchema); err != nil {
		return nil, fmt.Errorf("verify current SQLite schema: %w", err)
	}
	return &CurrentStore{db: db}, nil
}

func (s *CurrentStore) Close() error { return s.db.Close() }

// CloseAdmission is durable, including when startup fails before SIP loading.
func (s *CurrentStore) CloseAdmission(dispatcherID string) error {
	if dispatcherID == "" {
		return errors.New("dispatcher ID is required")
	}
	if _, err := s.db.Exec(`INSERT INTO dispatcher_state(dispatcher_id,discovery_ready) VALUES(?,0)
        ON CONFLICT(dispatcher_id) DO UPDATE SET discovery_ready=0`, dispatcherID); err != nil {
		return fmt.Errorf("close task admission: %w", err)
	}
	return nil
}

// ApplyDiscoverySnapshot commits the entire cold-start list in one transaction.
// It closes admission until the caller has drained the control queue.
func (s *CurrentStore) ApplyDiscoverySnapshot(dispatcherID string, tasks []configread.CurrentDiscoveredTask) (err error) {
	if dispatcherID == "" {
		return errors.New("dispatcher ID is required")
	}
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	if _, err = tx.Exec(`INSERT INTO dispatcher_state(dispatcher_id,discovery_ready) VALUES(?,0)
        ON CONFLICT(dispatcher_id) DO UPDATE SET discovery_ready=0`, dispatcherID); err != nil {
		return fmt.Errorf("close discovery admission: %w", err)
	}
	if _, err = tx.Exec(`UPDATE dispatcher_tasks SET present=0 WHERE dispatcher_id=?`, dispatcherID); err != nil {
		return fmt.Errorf("invalidate previous discovery list: %w", err)
	}
	if err := applyDiscoveredTasks(tx, dispatcherID, tasks); err != nil {
		return err
	}
	return tx.Commit()
}

// ApplyDiscoveryPage commits one delta page before its in-memory cursor may
// advance. It never treats tasks absent from a delta page as retired.
func (s *CurrentStore) ApplyDiscoveryPage(dispatcherID string, tasks []configread.CurrentDiscoveredTask) error {
	if dispatcherID == "" || len(tasks) == 0 {
		return errors.New("discovery delta requires a Dispatcher and nonempty page")
	}
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	if err := applyDiscoveredTasks(tx, dispatcherID, tasks); err != nil {
		return err
	}
	if err := tx.Commit(); err != nil {
		return fmt.Errorf("commit discovery page: %w", err)
	}
	return nil
}

func applyDiscoveredTasks(tx *sql.Tx, dispatcherID string, tasks []configread.CurrentDiscoveredTask) error {
	seen := make(map[string]struct{}, len(tasks))
	for _, task := range tasks {
		if task.TaskID == "" || task.TenantID <= 0 || task.TaskRevision <= 0 || !validTaskStatus(task.Status) {
			return fmt.Errorf("invalid discovered task %q", task.TaskID)
		}
		if _, exists := seen[task.TaskID]; exists {
			return fmt.Errorf("duplicate discovered task %q", task.TaskID)
		}
		seen[task.TaskID] = struct{}{}
		var otherTenant int64
		err := tx.QueryRow(`SELECT tenant_id FROM dispatcher_tasks WHERE dispatcher_id=? AND task_id=? AND tenant_id<>? LIMIT 1`, dispatcherID, task.TaskID, task.TenantID).Scan(&otherTenant)
		if err == nil {
			return fmt.Errorf("task %q was previously assigned to a different tenant", task.TaskID)
		}
		if !errors.Is(err, sql.ErrNoRows) {
			return fmt.Errorf("check task %q tenant ownership: %w", task.TaskID, err)
		}
		var oldRevision int64
		err = tx.QueryRow(`SELECT task_revision FROM dispatcher_tasks WHERE dispatcher_id=? AND tenant_id=? AND task_id=?`, dispatcherID, task.TenantID, task.TaskID).Scan(&oldRevision)
		if err != nil && !errors.Is(err, sql.ErrNoRows) {
			return fmt.Errorf("check task %q discovery revision: %w", task.TaskID, err)
		}
		if err == nil && task.TaskRevision < oldRevision {
			return fmt.Errorf("task %q discovery revision regressed", task.TaskID)
		}
		initialControl := ""
		if task.Status == "paused" || task.Status == "stopped" {
			initialControl = task.Status
		}
		if _, err = tx.Exec(`INSERT INTO dispatcher_tasks(dispatcher_id,tenant_id,task_id,task_revision,status,present,control_state)
            VALUES(?,?,?,?,?,1,?) ON CONFLICT(dispatcher_id,tenant_id,task_id)
            DO UPDATE SET task_revision=excluded.task_revision,
              status=CASE WHEN dispatcher_tasks.status='stopped' OR dispatcher_tasks.control_state IN ('stopping','stopped') THEN 'stopped' ELSE excluded.status END,
              present=1,
              control_state=CASE
                WHEN dispatcher_tasks.status='stopped' OR dispatcher_tasks.control_state IN ('stopping','stopped') OR excluded.status='stopped' THEN 'stopped'
                WHEN dispatcher_tasks.control_state<>'' THEN dispatcher_tasks.control_state
                WHEN excluded.status='paused' THEN 'paused'
                ELSE '' END`, dispatcherID, task.TenantID, task.TaskID, task.TaskRevision, task.Status, initialControl); err != nil {
			return fmt.Errorf("persist discovered task %q: %w", task.TaskID, err)
		}
		if task.Status == "stopped" || initialControl == "stopped" {
			if _, err := tx.Exec(`UPDATE dispatcher_inbox SET status='suppressed' WHERE dispatcher_id=? AND tenant_id=? AND task_id=? AND status='pending'`, dispatcherID, task.TenantID, task.TaskID); err != nil {
				return fmt.Errorf("suppress stopped task %q pending calls: %w", task.TaskID, err)
			}
		}
	}
	return nil
}

func validTaskStatus(status string) bool {
	return status == "running" || status == "paused" || status == "stopped"
}

type CurrentAssignedTask struct {
	TenantID     int64
	TaskID       string
	TaskRevision int64
	Status       string
	ControlState string
}

// ListAssignedTasks is used to attach only the task queues assigned to this
// Dispatcher. Stopped task queues can still drain old, unaccepted commands.
func (s *CurrentStore) ListAssignedTasks(dispatcherID string) ([]CurrentAssignedTask, error) {
	rows, err := s.db.Query(`SELECT tenant_id,task_id,task_revision,status,control_state FROM dispatcher_tasks
        WHERE dispatcher_id=? AND present=1 ORDER BY task_id`, dispatcherID)
	if err != nil {
		return nil, fmt.Errorf("list assigned task queues: %w", err)
	}
	defer rows.Close()
	var assigned []CurrentAssignedTask
	for rows.Next() {
		var task CurrentAssignedTask
		if err := rows.Scan(&task.TenantID, &task.TaskID, &task.TaskRevision, &task.Status, &task.ControlState); err != nil {
			return nil, fmt.Errorf("read assigned task queue: %w", err)
		}
		assigned = append(assigned, task)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("list assigned task queues: %w", err)
	}
	return assigned, nil
}

// CanAdmit checks persisted discovery and human controls; it does not replace
// call-time whitelist, schedule, SIP load, quota or authorization checks.
func (s *CurrentStore) CanAdmit(dispatcherID string, tenantID int64, taskID string) (bool, error) {
	var count int
	err := s.db.QueryRow(`SELECT COUNT(*) FROM dispatcher_tasks t
        JOIN dispatcher_state ds ON ds.dispatcher_id=t.dispatcher_id
        JOIN dispatcher_configs c ON c.dispatcher_id=t.dispatcher_id AND c.tenant_id=t.tenant_id AND c.task_id=t.task_id AND c.task_revision=t.task_revision
        WHERE t.dispatcher_id=? AND t.tenant_id=? AND t.task_id=? AND t.present=1
          AND t.status='running' AND t.control_state='' AND ds.discovery_ready=1`, dispatcherID, tenantID, taskID).Scan(&count)
	if err != nil {
		return false, fmt.Errorf("check durable task admission: %w", err)
	}
	return count == 1, nil
}

// SaveSnapshot refuses an immutable task revision with different content. Only
// the providers actually referenced by this task are included in its digest.
func (s *CurrentStore) SaveSnapshot(snapshot configread.CurrentSnapshot) error {
	task := snapshot.Task
	if task.DispatcherID == "" || task.TenantID <= 0 || task.TaskID == "" || task.TaskRevision <= 0 || snapshot.SIP.DispatcherID != task.DispatcherID || snapshot.Quota.DispatcherID != task.DispatcherID || snapshot.Quota.TenantID != task.TenantID || snapshot.SIP.Revision <= 0 || snapshot.Quota.QuotaRevision <= 0 || !json.Valid(task.Raw) {
		return errors.New("invalid current task snapshot identity, revision, or body")
	}
	providers := make(map[string]configread.CurrentProvider)
	for _, ref := range []string{task.Agent.ASR.ProviderRef, task.Agent.LLM.ProviderRef, task.Agent.TTS.ProviderRef} {
		if ref == "" {
			continue
		}
		provider, ok := snapshot.Providers[ref]
		if !ok || !provider.Enabled || provider.Credential == "" {
			return fmt.Errorf("task provider %q is unavailable", ref)
		}
		providers[ref] = provider
	}
	var canonicalTask any
	decoder := json.NewDecoder(bytes.NewReader(task.Raw))
	decoder.UseNumber()
	if err := decoder.Decode(&canonicalTask); err != nil {
		return fmt.Errorf("decode immutable task: %w", err)
	}
	binding, err := json.Marshal(struct {
		Task      any                                   `json:"task"`
		Providers map[string]configread.CurrentProvider `json:"providers"`
	}{canonicalTask, providers})
	if err != nil {
		return fmt.Errorf("encode immutable task binding: %w", err)
	}
	full, err := json.Marshal(struct {
		Task      any                                   `json:"task"`
		Providers map[string]configread.CurrentProvider `json:"providers"`
		SIP       configread.CurrentSIP                 `json:"sip"`
		Quota     configread.CurrentQuota               `json:"quota"`
	}{canonicalTask, providers, snapshot.SIP, snapshot.Quota})
	if err != nil {
		return fmt.Errorf("encode task execution snapshot: %w", err)
	}
	sum := sha256.Sum256(binding)
	digest := hex.EncodeToString(sum[:])
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	if err := validateCurrentGlobalRevisions(tx, snapshot); err != nil {
		return err
	}
	var oldRevision int64
	var oldDigest string
	err = tx.QueryRow(`SELECT task_revision,content_sha256 FROM dispatcher_configs WHERE dispatcher_id=? AND tenant_id=? AND task_id=?`, task.DispatcherID, task.TenantID, task.TaskID).Scan(&oldRevision, &oldDigest)
	if err != nil && !errors.Is(err, sql.ErrNoRows) {
		return fmt.Errorf("read immutable snapshot version: %w", err)
	}
	if err == nil {
		if oldRevision > task.TaskRevision {
			return fmt.Errorf("task %q revision regressed", task.TaskID)
		}
		if oldRevision == task.TaskRevision && oldDigest != digest {
			return fmt.Errorf("task %q revision %d changed content", task.TaskID, task.TaskRevision)
		}
		if oldRevision == task.TaskRevision {
			if _, err := tx.Exec(`UPDATE dispatcher_configs SET sip_revision=?,quota_revision=?,snapshot_json=? WHERE dispatcher_id=? AND tenant_id=? AND task_id=?`, snapshot.SIP.Revision, snapshot.Quota.QuotaRevision, full, task.DispatcherID, task.TenantID, task.TaskID); err != nil {
				return fmt.Errorf("refresh global SIP/quota for task %q: %w", task.TaskID, err)
			}
			return tx.Commit()
		}
	}
	if _, err = tx.Exec(`INSERT INTO dispatcher_configs(dispatcher_id,tenant_id,task_id,task_revision,sip_revision,quota_revision,content_sha256,snapshot_json)
        VALUES(?,?,?,?,?,?,?,?) ON CONFLICT(dispatcher_id,tenant_id,task_id) DO UPDATE SET
        task_revision=excluded.task_revision,sip_revision=excluded.sip_revision,quota_revision=excluded.quota_revision,
        content_sha256=excluded.content_sha256,snapshot_json=excluded.snapshot_json`, task.DispatcherID, task.TenantID, task.TaskID, task.TaskRevision, snapshot.SIP.Revision, snapshot.Quota.QuotaRevision, digest, full); err != nil {
		return fmt.Errorf("persist task snapshot %q: %w", task.TaskID, err)
	}
	return tx.Commit()
}

// validateCurrentGlobalRevisions prevents two task bindings from silently
// disagreeing about the same approved Dispatcher SIP or tenant quota revision.
// Older revisions also cannot replace a newer binding across tasks.
func validateCurrentGlobalRevisions(tx *sql.Tx, snapshot configread.CurrentSnapshot) error {
	newSIP, err := json.Marshal(snapshot.SIP)
	if err != nil {
		return fmt.Errorf("encode approved SIP revision: %w", err)
	}
	newQuota, err := json.Marshal(snapshot.Quota)
	if err != nil {
		return fmt.Errorf("encode approved quota revision: %w", err)
	}
	rows, err := tx.Query(`SELECT tenant_id,task_id,sip_revision,quota_revision,snapshot_json FROM dispatcher_configs WHERE dispatcher_id=?`, snapshot.Task.DispatcherID)
	if err != nil {
		return fmt.Errorf("inspect current global revision bindings: %w", err)
	}
	defer rows.Close()
	for rows.Next() {
		var tenantID, sipRevision, quotaRevision int64
		var taskID string
		var raw []byte
		if err := rows.Scan(&tenantID, &taskID, &sipRevision, &quotaRevision, &raw); err != nil {
			return fmt.Errorf("read global revision binding: %w", err)
		}
		var old struct {
			SIP   configread.CurrentSIP   `json:"sip"`
			Quota configread.CurrentQuota `json:"quota"`
		}
		if err := json.Unmarshal(raw, &old); err != nil {
			return fmt.Errorf("decode global revision binding for task %q: %w", taskID, err)
		}
		if old.SIP.Revision != sipRevision || old.Quota.QuotaRevision != quotaRevision || old.Quota.TenantID != tenantID {
			return fmt.Errorf("stored global revision binding for task %q is inconsistent", taskID)
		}
		if sipRevision > snapshot.SIP.Revision {
			return fmt.Errorf("SIP revision regressed below task %q", taskID)
		}
		if sipRevision == snapshot.SIP.Revision {
			previous, err := json.Marshal(old.SIP)
			if err != nil {
				return fmt.Errorf("encode existing SIP revision: %w", err)
			}
			if !bytes.Equal(previous, newSIP) {
				return fmt.Errorf("SIP revision %d changed approved content across task %q", sipRevision, taskID)
			}
		}
		if tenantID != snapshot.Task.TenantID {
			continue
		}
		if quotaRevision > snapshot.Quota.QuotaRevision {
			return fmt.Errorf("tenant quota revision regressed below task %q", taskID)
		}
		if quotaRevision == snapshot.Quota.QuotaRevision {
			previous, err := json.Marshal(old.Quota)
			if err != nil {
				return fmt.Errorf("encode existing tenant quota revision: %w", err)
			}
			if !bytes.Equal(previous, newQuota) {
				return fmt.Errorf("tenant quota revision %d changed approved content across task %q", quotaRevision, taskID)
			}
		}
	}
	if err := rows.Err(); err != nil {
		return fmt.Errorf("read global revision bindings: %w", err)
	}
	return nil
}

// ReadSnapshot returns only the current durable binding. Corrupt or mismatched
// data is an error, never a signal to fetch an old contract instead.
func (s *CurrentStore) ReadSnapshot(dispatcherID string, tenantID int64, taskID string) (configread.CurrentSnapshot, error) {
	var body []byte
	var taskRevision, sipRevision, quotaRevision int64
	err := s.db.QueryRow(`SELECT task_revision,sip_revision,quota_revision,snapshot_json FROM dispatcher_configs WHERE dispatcher_id=? AND tenant_id=? AND task_id=?`, dispatcherID, tenantID, taskID).Scan(&taskRevision, &sipRevision, &quotaRevision, &body)
	if err != nil {
		return configread.CurrentSnapshot{}, fmt.Errorf("load task execution snapshot: %w", err)
	}
	var decoded struct {
		Task      json.RawMessage                       `json:"task"`
		Providers map[string]configread.CurrentProvider `json:"providers"`
		SIP       configread.CurrentSIP                 `json:"sip"`
		Quota     configread.CurrentQuota               `json:"quota"`
	}
	if err := json.Unmarshal(body, &decoded); err != nil {
		return configread.CurrentSnapshot{}, fmt.Errorf("decode task execution snapshot: %w", err)
	}
	var task configread.CurrentTask
	if err := json.Unmarshal(decoded.Task, &task); err != nil {
		return configread.CurrentSnapshot{}, fmt.Errorf("decode stored task configuration: %w", err)
	}
	if task.DispatcherID != dispatcherID || task.TenantID != tenantID || task.TaskID != taskID || task.TaskRevision != taskRevision || decoded.SIP.DispatcherID != dispatcherID || decoded.SIP.Revision != sipRevision || decoded.Quota.DispatcherID != dispatcherID || decoded.Quota.TenantID != tenantID || decoded.Quota.QuotaRevision != quotaRevision {
		return configread.CurrentSnapshot{}, errors.New("persisted task snapshot identity or revision mismatch")
	}
	return configread.CurrentSnapshot{Task: task, Providers: decoded.Providers, SIP: decoded.SIP, Quota: decoded.Quota}, nil
}

func (s *CurrentStore) ApplyControl(dispatcherID string, tenantID int64, taskID, action string) error {
	if dispatcherID == "" || tenantID <= 0 || taskID == "" {
		return errors.New("invalid task control identity")
	}
	var newState string
	var predicate string
	switch action {
	case "pause":
		newState, predicate = "paused", "control_state <> 'stopped'"
	case "stop":
		newState, predicate = "stopped", "1=1"
	case "resume":
		newState, predicate = "", `control_state='paused' AND status='running' AND EXISTS
            (SELECT 1 FROM dispatcher_configs c WHERE c.dispatcher_id=dispatcher_tasks.dispatcher_id
             AND c.tenant_id=dispatcher_tasks.tenant_id AND c.task_id=dispatcher_tasks.task_id
             AND c.task_revision=dispatcher_tasks.task_revision)`
	default:
		return fmt.Errorf("unknown task control action %q", action)
	}
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	query := `UPDATE dispatcher_tasks SET control_state=? WHERE dispatcher_id=? AND tenant_id=? AND task_id=? AND present=1 AND ` + predicate
	result, err := tx.Exec(query, newState, dispatcherID, tenantID, taskID)
	if err != nil {
		return fmt.Errorf("persist task control %q: %w", action, err)
	}
	n, err := result.RowsAffected()
	if err != nil {
		return err
	}
	if n != 1 {
		return fmt.Errorf("task control %q rejected for task %q", action, taskID)
	}
	if action == "stop" {
		if _, err := tx.Exec(`UPDATE dispatcher_inbox SET status='suppressed' WHERE dispatcher_id=? AND tenant_id=? AND task_id=? AND status='pending'`, dispatcherID, tenantID, taskID); err != nil {
			return fmt.Errorf("suppress unstarted stopped-task commands: %w", err)
		}
	}
	if err := tx.Commit(); err != nil {
		return fmt.Errorf("commit task control %q: %w", action, err)
	}
	return nil
}