package storage

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"github.com/kami/hexis/internal/domain"
	_ "modernc.org/sqlite"
)

type Store struct {
	mu   sync.RWMutex
	db   *sql.DB
	path string
}

func Open(path string) (*Store, error) {
	dir := filepath.Dir(path)
	if err := os.MkdirAll(dir, 0755); err != nil {
		return nil, fmt.Errorf("create directory: %w", err)
	}

	db, err := sql.Open("sqlite", path+"?_pragma=journal_mode(WAL)&_pragma=foreign_keys(1)")
	if err != nil {
		return nil, fmt.Errorf("open database: %w", err)
	}

	db.SetMaxOpenConns(1)

	store := &Store{db: db, path: path}
	if err := store.migrate(); err != nil {
		return nil, fmt.Errorf("migrate: %w", err)
	}
	return store, nil
}

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

func (s *Store) DB() *sql.DB {
	return s.db
}

func (s *Store) migrate() error {
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	var v int
	err = tx.QueryRow("PRAGMA user_version").Scan(&v)
	if err != nil {
		return err
	}

	if v < len(migrations) {
		for i, m := range migrations[v:] {
			if _, err := tx.Exec(m); err != nil {
				return fmt.Errorf("migration %d: %w", v+i+1, err)
			}
			if _, err := tx.Exec(fmt.Sprintf("PRAGMA user_version = %d", v+i+1)); err != nil {
				return err
			}
		}
	}

	return tx.Commit()
}

var migrations = []string{
	`CREATE TABLE IF NOT EXISTS capabilities (
		id TEXT PRIMARY KEY,
		name TEXT NOT NULL,
		description TEXT NOT NULL DEFAULT '',
		target_types TEXT NOT NULL DEFAULT '[]',
		target_entity_id TEXT NOT NULL DEFAULT '',
		provider TEXT NOT NULL,
		operation TEXT NOT NULL,
		risk TEXT NOT NULL DEFAULT '',
		read_only INTEGER NOT NULL DEFAULT 1,
		expected_side_effects TEXT NOT NULL DEFAULT '',
		attributes TEXT NOT NULL DEFAULT '{}',
		created_at TEXT NOT NULL,
		updated_at TEXT NOT NULL,
		version INTEGER NOT NULL DEFAULT 0
	)`,
	`CREATE TABLE IF NOT EXISTS executions (
		id TEXT PRIMARY KEY,
		capability_id TEXT NOT NULL,
		target_entity_id TEXT NOT NULL,
		entity_version INTEGER NOT NULL DEFAULT 0,
		arguments TEXT NOT NULL DEFAULT '{}',
		requested_by TEXT NOT NULL DEFAULT '{}',
		origin TEXT NOT NULL DEFAULT '{}',
		idempotency_key TEXT UNIQUE,
		status TEXT NOT NULL DEFAULT 'started',
		result TEXT NOT NULL DEFAULT '{}',
		error TEXT NOT NULL DEFAULT '',
		resolution_evidence TEXT NOT NULL DEFAULT '[]',
		correlation_id TEXT NOT NULL DEFAULT '',
		created_at TEXT NOT NULL,
		updated_at TEXT NOT NULL
	)`,
	`CREATE TABLE IF NOT EXISTS hexis_events (
		id TEXT PRIMARY KEY,
		sequence INTEGER NOT NULL,
		type TEXT NOT NULL,
		timestamp TEXT NOT NULL,
		actor TEXT NOT NULL DEFAULT '',
		correlation_id TEXT NOT NULL DEFAULT '',
		causation_id TEXT NOT NULL DEFAULT '',
		payload TEXT NOT NULL DEFAULT '{}'
	)`,
	`CREATE INDEX IF NOT EXISTS idx_hevents_sequence ON hexis_events(sequence)`,
	// Retired: schema_migrations was never read — PRAGMA user_version is the
	// real mechanism. Migrations are applied by slice index, so this slot must
	// keep its position or every later migration would be renumbered and
	// skipped on already-migrated databases. Left as a no-op instead.
	`SELECT 1`,
	`ALTER TABLE capabilities ADD COLUMN requires_confirmation INTEGER NOT NULL DEFAULT 0`,
	`ALTER TABLE capabilities ADD COLUMN enabled INTEGER NOT NULL DEFAULT 1`,
	`ALTER TABLE capabilities ADD COLUMN timeout_seconds INTEGER NOT NULL DEFAULT 30`,
	`ALTER TABLE executions ADD COLUMN confirmation_id TEXT NOT NULL DEFAULT ''`,
	`CREATE TABLE IF NOT EXISTS confirmations (
		id TEXT PRIMARY KEY,
		capability_id TEXT NOT NULL,
		capability_version INTEGER NOT NULL,
		target_entity_id TEXT NOT NULL,
		args_normalized TEXT NOT NULL DEFAULT '{}',
		args_hash TEXT NOT NULL,
		requester TEXT NOT NULL DEFAULT '',
		created_at TEXT NOT NULL,
		expires_at TEXT NOT NULL,
		state TEXT NOT NULL DEFAULT 'pending'
	)`,
	`CREATE INDEX IF NOT EXISTS idx_executions_inflight ON executions(capability_id, target_entity_id, status)`,
	// Audit columns missing from executions (spec §4.1) plus a partial UNIQUE
	// index enforcing one in-flight execution per (capability, target).
	// Pre-existing duplicate in-flight rows would make the index creation fail,
	// so they are resolved to 'unknown' first — that is the spec's outcome for
	// an execution whose side effect can no longer be determined.
	`ALTER TABLE executions ADD COLUMN causation_id TEXT NOT NULL DEFAULT '';
	 ALTER TABLE executions ADD COLUMN capability_version INTEGER NOT NULL DEFAULT 0;
	 UPDATE executions SET status = 'unknown'
	   WHERE status = 'started'
	     AND id NOT IN (
	       SELECT MIN(id) FROM executions WHERE status = 'started'
	       GROUP BY capability_id, target_entity_id
	     );
	 DROP INDEX IF EXISTS idx_executions_inflight;
	 CREATE UNIQUE INDEX IF NOT EXISTS idx_executions_inflight
	   ON executions(capability_id, target_entity_id) WHERE status = 'started';`,
	// Supports the entity_id filter on GET /api/v1/executions (spec §4.5). The
	// `since` cursor is the row's implicit rowid, which cannot appear in an
	// index (SQLite indexes it as the btree key already), so ordering and
	// range-scanning by rowid needs no index of its own.
	`CREATE INDEX IF NOT EXISTS idx_executions_entity ON executions(target_entity_id)`,
}

const timeFmt = "2006-01-02T15:04:05.999999999Z07:00"

func formatTime(t time.Time) string {
	return t.UTC().Format(timeFmt)
}

func parseTime(s string) time.Time {
	t, err := time.Parse(timeFmt, s)
	if err != nil {
		t, err = time.Parse(time.RFC3339, s)
		if err != nil {
			return time.Time{}
		}
	}
	return t
}

// Capability operations

func (s *Store) CreateCapability(c *domain.Capability) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	targetTypes, _ := json.Marshal(c.TargetTypes)
	attrs, _ := json.Marshal(c.Attributes)

	_, err := s.db.Exec(
		`INSERT INTO capabilities (id, name, description, target_types, target_entity_id, provider, operation, risk, read_only, expected_side_effects, requires_confirmation, enabled, timeout_seconds, attributes, created_at, updated_at, version)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
		c.ID, c.Name, c.Description, string(targetTypes), c.TargetEntityID, c.Provider, c.Operation, c.Risk, boolInt(c.ReadOnly), c.ExpectedSideEffects, boolInt(c.RequiresConfirmation), boolInt(c.Enabled), c.TimeoutSeconds, string(attrs), formatTime(c.CreatedAt), formatTime(c.UpdatedAt), c.Version,
	)
	return err
}

func (s *Store) GetCapability(id string) (*domain.Capability, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()

	row := s.db.QueryRow(
		`SELECT id, name, description, target_types, COALESCE(target_entity_id,''), provider, operation, risk, read_only, COALESCE(expected_side_effects,''), requires_confirmation, enabled, timeout_seconds, attributes, created_at, updated_at, version
		 FROM capabilities WHERE id = ?`, id,
	)
	c := &domain.Capability{}
	var targetTypes, attrs, createdAt, updatedAt string
	err := row.Scan(&c.ID, &c.Name, &c.Description, &targetTypes, &c.TargetEntityID, &c.Provider, &c.Operation, &c.Risk, &c.ReadOnly, &c.ExpectedSideEffects, &c.RequiresConfirmation, &c.Enabled, &c.TimeoutSeconds, &attrs, &createdAt, &updatedAt, &c.Version)
	if err == sql.ErrNoRows {
		return nil, domain.ErrCapabilityNotFound
	}
	if err != nil {
		return nil, err
	}
	json.Unmarshal([]byte(targetTypes), &c.TargetTypes)
	json.Unmarshal([]byte(attrs), &c.Attributes)
	c.CreatedAt = parseTime(createdAt)
	c.UpdatedAt = parseTime(updatedAt)
	if c.TargetTypes == nil {
		c.TargetTypes = []string{}
	}
	if c.Attributes == nil {
		c.Attributes = map[string]any{}
	}
	return c, nil
}

func (s *Store) UpdateCapability(c *domain.Capability) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	targetTypes, _ := json.Marshal(c.TargetTypes)
	attrs, _ := json.Marshal(c.Attributes)

	res, err := s.db.Exec(
		`UPDATE capabilities SET name=?, description=?, target_types=?, target_entity_id=?, provider=?, operation=?, risk=?, read_only=?, expected_side_effects=?, requires_confirmation=?, enabled=?, timeout_seconds=?, attributes=?, updated_at=?, version=version+1
		 WHERE id=? AND version=?`,
		c.Name, c.Description, string(targetTypes), c.TargetEntityID, c.Provider, c.Operation, c.Risk, boolInt(c.ReadOnly), c.ExpectedSideEffects, boolInt(c.RequiresConfirmation), boolInt(c.Enabled), c.TimeoutSeconds, string(attrs), formatTime(c.UpdatedAt), c.ID, c.Version,
	)
	if err != nil {
		return err
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return domain.ErrConflict
	}
	c.Version++
	return nil
}

func (s *Store) ListCapabilities(entityID string) ([]*domain.Capability, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()

	query := `SELECT id, name, description, target_types, COALESCE(target_entity_id,''), provider, operation, risk, read_only, COALESCE(expected_side_effects,''), requires_confirmation, enabled, timeout_seconds, attributes, created_at, updated_at, version
		FROM capabilities`
	args := []any{}
	if entityID != "" {
		query += " WHERE target_entity_id = ?"
		args = append(args, entityID)
	}
	query += " ORDER BY name ASC"

	rows, err := s.db.Query(query, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var result []*domain.Capability
	for rows.Next() {
		c := &domain.Capability{}
		var targetTypes, attrs, createdAt, updatedAt string
		if err := rows.Scan(&c.ID, &c.Name, &c.Description, &targetTypes, &c.TargetEntityID, &c.Provider, &c.Operation, &c.Risk, &c.ReadOnly, &c.ExpectedSideEffects, &c.RequiresConfirmation, &c.Enabled, &c.TimeoutSeconds, &attrs, &createdAt, &updatedAt, &c.Version); err != nil {
			return nil, err
		}
		json.Unmarshal([]byte(targetTypes), &c.TargetTypes)
		json.Unmarshal([]byte(attrs), &c.Attributes)
		c.CreatedAt = parseTime(createdAt)
		c.UpdatedAt = parseTime(updatedAt)
		if c.TargetTypes == nil {
			c.TargetTypes = []string{}
		}
		if c.Attributes == nil {
			c.Attributes = map[string]any{}
		}
		result = append(result, c)
	}
	return result, nil
}

func (s *Store) DeleteCapability(id string) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	_, err := s.db.Exec(`DELETE FROM capabilities WHERE id = ?`, id)
	return err
}

// Execution operations

func (s *Store) CreateExecution(e *domain.Execution) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	args, _ := json.Marshal(e.Arguments)
	reqBy, _ := json.Marshal(e.RequestedBy)
	origin, _ := json.Marshal(e.Origin)
	result, _ := json.Marshal(e.Result)
	evidence, _ := json.Marshal(e.ResolutionEvidence)

	_, err := s.db.Exec(
		`INSERT INTO executions (id, capability_id, capability_version, target_entity_id, entity_version, arguments, requested_by, origin, idempotency_key, confirmation_id, status, result, error, resolution_evidence, correlation_id, causation_id, created_at, updated_at)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
		e.ID, e.CapabilityID, e.CapabilityVersion, e.TargetEntityID, e.EntityVersion, string(args), string(reqBy), string(origin), nullString(e.IdempotencyKey), e.ConfirmationID, string(e.Status), string(result), e.Error, string(evidence), e.CorrelationID, e.CausationID, formatTime(e.CreatedAt), formatTime(e.UpdatedAt),
	)
	if err != nil {
		if strings.Contains(err.Error(), "UNIQUE") {
			// The partial unique index on (capability_id, target_entity_id)
			// WHERE status='started' is the in-flight guard, not a replay.
			if strings.Contains(err.Error(), "idempotency_key") {
				return domain.ErrIdempotencyReplay
			}
			if strings.Contains(err.Error(), "capability_id") || strings.Contains(err.Error(), "target_entity_id") {
				return domain.ErrExecutionInFlight
			}
			return domain.ErrIdempotencyReplay
		}
		return err
	}
	return nil
}

func (s *Store) GetExecution(id string) (*domain.Execution, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()

	row := s.db.QueryRow(
		`SELECT id, capability_id, capability_version, target_entity_id, entity_version, arguments, requested_by, origin, COALESCE(idempotency_key,''), COALESCE(confirmation_id,''), status, result, COALESCE(error,''), resolution_evidence, COALESCE(correlation_id,''), COALESCE(causation_id,''), created_at, updated_at
		 FROM executions WHERE id = ?`, id,
	)
	e := &domain.Execution{}
	var args, reqBy, origin, idempKey, confID, status, result, errStr, evidence, corrID, causID, createdAt, updatedAt string
	err := row.Scan(&e.ID, &e.CapabilityID, &e.CapabilityVersion, &e.TargetEntityID, &e.EntityVersion, &args, &reqBy, &origin, &idempKey, &confID, &status, &result, &errStr, &evidence, &corrID, &causID, &createdAt, &updatedAt)
	if err == sql.ErrNoRows {
		return nil, domain.ErrExecutionNotFound
	}
	if err != nil {
		return nil, err
	}
	json.Unmarshal([]byte(args), &e.Arguments)
	json.Unmarshal([]byte(reqBy), &e.RequestedBy)
	json.Unmarshal([]byte(origin), &e.Origin)
	json.Unmarshal([]byte(result), &e.Result)
	json.Unmarshal([]byte(evidence), &e.ResolutionEvidence)
	e.IdempotencyKey = idempKey
	e.ConfirmationID = confID
	e.Status = domain.ExecutionStatus(status)
	e.Error = errStr
	e.CorrelationID = corrID
	e.CausationID = causID
	e.CreatedAt = parseTime(createdAt)
	e.UpdatedAt = parseTime(updatedAt)
	if e.Arguments == nil {
		e.Arguments = map[string]any{}
	}
	if e.RequestedBy == nil {
		e.RequestedBy = map[string]string{}
	}
	if e.Origin == nil {
		e.Origin = map[string]string{}
	}
	if e.Result == nil {
		e.Result = map[string]any{}
	}
	return e, nil
}

func (s *Store) UpdateExecution(e *domain.Execution) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	result, _ := json.Marshal(e.Result)

	_, err := s.db.Exec(
		`UPDATE executions SET status=?, result=?, error=?, updated_at=? WHERE id=?`,
		string(e.Status), string(result), e.Error, formatTime(e.UpdatedAt), e.ID,
	)
	return err
}

func (s *Store) GetExecutionByIdempotencyKey(key string) (*domain.Execution, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()

	row := s.db.QueryRow(
		`SELECT id, capability_id, capability_version, target_entity_id, entity_version, arguments, requested_by, origin, COALESCE(idempotency_key,''), COALESCE(confirmation_id,''), status, result, COALESCE(error,''), resolution_evidence, COALESCE(correlation_id,''), COALESCE(causation_id,''), created_at, updated_at
		 FROM executions WHERE idempotency_key = ?`, key,
	)
	e := &domain.Execution{}
	var args, reqBy, origin, idempKey, confID, status, result, errStr, evidence, corrID, causID, createdAt, updatedAt string
	err := row.Scan(&e.ID, &e.CapabilityID, &e.CapabilityVersion, &e.TargetEntityID, &e.EntityVersion, &args, &reqBy, &origin, &idempKey, &confID, &status, &result, &errStr, &evidence, &corrID, &causID, &createdAt, &updatedAt)
	if err == sql.ErrNoRows {
		return nil, domain.ErrExecutionNotFound
	}
	if err != nil {
		return nil, err
	}
	json.Unmarshal([]byte(args), &e.Arguments)
	json.Unmarshal([]byte(reqBy), &e.RequestedBy)
	json.Unmarshal([]byte(origin), &e.Origin)
	json.Unmarshal([]byte(result), &e.Result)
	json.Unmarshal([]byte(evidence), &e.ResolutionEvidence)
	e.IdempotencyKey = idempKey
	e.ConfirmationID = confID
	e.Status = domain.ExecutionStatus(status)
	e.Error = errStr
	e.CorrelationID = corrID
	e.CausationID = causID
	e.CreatedAt = parseTime(createdAt)
	e.UpdatedAt = parseTime(updatedAt)
	return e, nil
}

func (s *Store) GetInFlightExecution(capabilityID, targetEntityID string) (*domain.Execution, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()

	row := s.db.QueryRow(
		`SELECT id FROM executions WHERE capability_id = ? AND target_entity_id = ? AND status = ? LIMIT 1`,
		capabilityID, targetEntityID, string(domain.ExecutionStarted),
	)
	var id string
	err := row.Scan(&id)
	if err == sql.ErrNoRows {
		return nil, domain.ErrExecutionNotFound
	}
	if err != nil {
		return nil, err
	}
	return s.getExecutionLocked(id)
}

// getExecutionLocked reads an execution without acquiring s.mu; callers must
// already hold it (read or write).
func (s *Store) getExecutionLocked(id string) (*domain.Execution, error) {
	row := s.db.QueryRow(
		`SELECT id, capability_id, capability_version, target_entity_id, entity_version, arguments, requested_by, origin, COALESCE(idempotency_key,''), COALESCE(confirmation_id,''), status, result, COALESCE(error,''), resolution_evidence, COALESCE(correlation_id,''), COALESCE(causation_id,''), created_at, updated_at
		 FROM executions WHERE id = ?`, id,
	)
	e := &domain.Execution{}
	var args, reqBy, origin, idempKey, confID, status, result, errStr, evidence, corrID, causID, createdAt, updatedAt string
	err := row.Scan(&e.ID, &e.CapabilityID, &e.CapabilityVersion, &e.TargetEntityID, &e.EntityVersion, &args, &reqBy, &origin, &idempKey, &confID, &status, &result, &errStr, &evidence, &corrID, &causID, &createdAt, &updatedAt)
	if err == sql.ErrNoRows {
		return nil, domain.ErrExecutionNotFound
	}
	if err != nil {
		return nil, err
	}
	json.Unmarshal([]byte(args), &e.Arguments)
	json.Unmarshal([]byte(reqBy), &e.RequestedBy)
	json.Unmarshal([]byte(origin), &e.Origin)
	json.Unmarshal([]byte(result), &e.Result)
	json.Unmarshal([]byte(evidence), &e.ResolutionEvidence)
	e.IdempotencyKey = idempKey
	e.ConfirmationID = confID
	e.Status = domain.ExecutionStatus(status)
	e.Error = errStr
	e.CorrelationID = corrID
	e.CausationID = causID
	e.CreatedAt = parseTime(createdAt)
	e.UpdatedAt = parseTime(updatedAt)
	return e, nil
}

// executionColumns is the shared SELECT list for execution reads. `rowid` is
// the insertion sequence and doubles as the pagination cursor for
// ListExecutions; single-row reads ignore it.
//
// Using rowid as the cursor is safe here because executions is an ordinary
// rowid table (its PRIMARY KEY is TEXT, so rowid is a separate hidden counter)
// and nothing in this service deletes execution rows or runs VACUUM — both of
// which could renumber rowids and invalidate outstanding cursors. If either
// ever becomes true, promote this to an explicit monotonic seq column.
const executionColumns = `rowid, id, capability_id, capability_version, target_entity_id, entity_version, arguments, requested_by, origin, COALESCE(idempotency_key,''), COALESCE(confirmation_id,''), status, result, COALESCE(error,''), resolution_evidence, COALESCE(correlation_id,''), COALESCE(causation_id,''), created_at, updated_at`

// scanExecution reads one row selected with executionColumns.
func scanExecution(sc interface{ Scan(...any) error }) (*domain.Execution, error) {
	e := &domain.Execution{}
	var args, reqBy, origin, idempKey, confID, status, result, errStr, evidence, corrID, causID, createdAt, updatedAt string
	err := sc.Scan(&e.Seq, &e.ID, &e.CapabilityID, &e.CapabilityVersion, &e.TargetEntityID, &e.EntityVersion, &args, &reqBy, &origin, &idempKey, &confID, &status, &result, &errStr, &evidence, &corrID, &causID, &createdAt, &updatedAt)
	if err != nil {
		return nil, err
	}
	json.Unmarshal([]byte(args), &e.Arguments)
	json.Unmarshal([]byte(reqBy), &e.RequestedBy)
	json.Unmarshal([]byte(origin), &e.Origin)
	json.Unmarshal([]byte(result), &e.Result)
	json.Unmarshal([]byte(evidence), &e.ResolutionEvidence)
	e.IdempotencyKey = idempKey
	e.ConfirmationID = confID
	e.Status = domain.ExecutionStatus(status)
	e.Error = errStr
	e.CorrelationID = corrID
	e.CausationID = causID
	e.CreatedAt = parseTime(createdAt)
	e.UpdatedAt = parseTime(updatedAt)
	if e.Arguments == nil {
		e.Arguments = map[string]any{}
	}
	if e.RequestedBy == nil {
		e.RequestedBy = map[string]string{}
	}
	if e.Origin == nil {
		e.Origin = map[string]string{}
	}
	if e.Result == nil {
		e.Result = map[string]any{}
	}
	return e, nil
}

// MaxExecutionPageSize bounds a single ListExecutions page, matching the
// 100-row cap the changes feed uses.
const MaxExecutionPageSize = 100

// ListExecutions returns executions ordered by ascending insertion sequence.
//
// entityID, when non-empty, restricts to that target entity. sinceSeq is an
// exclusive cursor: only rows with Seq > sinceSeq are returned, the same
// convention as EventsAfter on /api/v1/changes. limit is clamped to
// MaxExecutionPageSize.
func (s *Store) ListExecutions(entityID string, sinceSeq int64, limit int) ([]*domain.Execution, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()

	if limit <= 0 || limit > MaxExecutionPageSize {
		limit = MaxExecutionPageSize
	}

	query := `SELECT ` + executionColumns + ` FROM executions WHERE rowid > ?`
	args := []any{sinceSeq}
	if entityID != "" {
		query += ` AND target_entity_id = ?`
		args = append(args, entityID)
	}
	query += ` ORDER BY rowid ASC LIMIT ?`
	args = append(args, limit)

	rows, err := s.db.Query(query, args...)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	out := []*domain.Execution{}
	for rows.Next() {
		e, err := scanExecution(rows)
		if err != nil {
			return nil, err
		}
		out = append(out, e)
	}
	return out, rows.Err()
}

// Confirmation operations

func (s *Store) CreateConfirmation(c *domain.Confirmation) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	_, err := s.db.Exec(
		`INSERT INTO confirmations (id, capability_id, capability_version, target_entity_id, args_normalized, args_hash, requester, created_at, expires_at, state)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
		c.ID, c.CapabilityID, c.CapabilityVersion, c.TargetEntityID, c.ArgsNormalized, c.ArgsHash, c.Requester, formatTime(c.CreatedAt), formatTime(c.ExpiresAt), string(c.State),
	)
	return err
}

func (s *Store) GetConfirmation(id string) (*domain.Confirmation, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()

	row := s.db.QueryRow(
		`SELECT id, capability_id, capability_version, target_entity_id, args_normalized, args_hash, requester, created_at, expires_at, state
		 FROM confirmations WHERE id = ?`, id,
	)
	c := &domain.Confirmation{}
	var createdAt, expiresAt, state string
	err := row.Scan(&c.ID, &c.CapabilityID, &c.CapabilityVersion, &c.TargetEntityID, &c.ArgsNormalized, &c.ArgsHash, &c.Requester, &createdAt, &expiresAt, &state)
	if err == sql.ErrNoRows {
		return nil, domain.ErrConfirmationNotFound
	}
	if err != nil {
		return nil, err
	}
	c.CreatedAt = parseTime(createdAt)
	c.ExpiresAt = parseTime(expiresAt)
	c.State = domain.ConfirmationState(state)
	return c, nil
}

func (s *Store) UpdateConfirmationState(id string, state domain.ConfirmationState) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	_, err := s.db.Exec(`UPDATE confirmations SET state = ? WHERE id = ?`, string(state), id)
	return err
}

// Event operations

func (s *Store) AppendEvent(evt *domain.Event) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	var maxSeq sql.NullInt64
	s.db.QueryRow(`SELECT MAX(sequence) FROM hexis_events`).Scan(&maxSeq)
	evt.Sequence = maxSeq.Int64 + 1

	payload, _ := json.Marshal(evt.Payload)

	_, err := s.db.Exec(
		`INSERT INTO hexis_events (id, sequence, type, timestamp, actor, correlation_id, causation_id, payload)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
		evt.ID, evt.Sequence, string(evt.Type), formatTime(evt.Timestamp), evt.Actor, evt.CorrelationID, evt.CausationID, string(payload),
	)
	return err
}

func (s *Store) EventsAfter(seq int64, limit int) ([]*domain.Event, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()

	rows, err := s.db.Query(
		`SELECT id, sequence, type, timestamp, COALESCE(actor,''), COALESCE(correlation_id,''), COALESCE(causation_id,''), payload
		 FROM hexis_events WHERE sequence > ? ORDER BY sequence LIMIT ?`, seq, limit,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var result []*domain.Event
	for rows.Next() {
		e := &domain.Event{}
		var typ, payload, timestamp string
		if err := rows.Scan(&e.ID, &e.Sequence, &typ, &timestamp, &e.Actor, &e.CorrelationID, &e.CausationID, &payload); err != nil {
			return nil, err
		}
		e.Type = domain.HexisEventType(typ)
		e.Timestamp = parseTime(timestamp)
		json.Unmarshal([]byte(payload), &e.Payload)
		result = append(result, e)
	}
	return result, nil
}

func (s *Store) LatestSequence() (int64, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()

	var seq sql.NullInt64
	s.db.QueryRow(`SELECT MAX(sequence) FROM hexis_events`).Scan(&seq)
	return seq.Int64, nil
}

func nullString(s string) interface{} {
	if s == "" {
		return nil
	}
	return s
}

func boolInt(b bool) int {
	if b {
		return 1
	}
	return 0
}

var _ Interface = (*Store)(nil)