package store

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"time"

	"gitea.stevedudenhoeffer.com/steve/executus/persona"
)

// personaStore is the SQLite-backed persona.Storage. It stores each Agent as a
// JSON blob in `data` with a handful of extracted, indexed columns for the
// query methods — so the FULL struct round-trips (no domain↔GORM↔DB field-loss
// footgun) while owner/name/webhook/schedule lookups stay indexable.
type personaStore struct{ db *sql.DB }

// Personas returns a durable persona.Storage backed by this database.
func (d *DB) Personas() persona.Storage { return &personaStore{db: d.sql} }

var _ persona.Storage = (*personaStore)(nil)

func (s *personaStore) InitializeAgentStorage(ctx context.Context) error {
	_, err := s.db.ExecContext(ctx, `
CREATE TABLE IF NOT EXISTS agents (
	id                     TEXT PRIMARY KEY,
	owner_id               TEXT NOT NULL DEFAULT '',
	name                   TEXT NOT NULL DEFAULT '',
	webhook_secret         TEXT NOT NULL DEFAULT '',
	chatbot_channel_filter TEXT NOT NULL DEFAULT '',
	schedule               TEXT NOT NULL DEFAULT '',
	next_run_at            INTEGER NOT NULL DEFAULT 0, -- unix seconds; 0 = unset
	data                   TEXT NOT NULL              -- full Agent as JSON
);
CREATE INDEX IF NOT EXISTS idx_agents_owner ON agents(owner_id);
CREATE UNIQUE INDEX IF NOT EXISTS idx_agents_owner_name ON agents(owner_id, name);
CREATE INDEX IF NOT EXISTS idx_agents_sched ON agents(schedule, next_run_at);`)
	if err != nil {
		return fmt.Errorf("personaStore.Initialize: %w", err)
	}
	return nil
}

func (s *personaStore) SaveAgent(ctx context.Context, a *persona.Agent) error {
	blob, err := json.Marshal(a)
	if err != nil {
		return fmt.Errorf("personaStore.SaveAgent: marshal: %w", err)
	}
	var next int64
	if a.NextRunAt != nil && !a.NextRunAt.IsZero() {
		next = a.NextRunAt.Unix()
	}
	_, err = s.db.ExecContext(ctx, `
INSERT INTO agents (id, owner_id, name, webhook_secret, chatbot_channel_filter, schedule, next_run_at, data)
VALUES (?, ?, ?, ?, ?, ?, ?, ?)
ON CONFLICT(id) DO UPDATE SET
	owner_id=excluded.owner_id, name=excluded.name, webhook_secret=excluded.webhook_secret,
	chatbot_channel_filter=excluded.chatbot_channel_filter, schedule=excluded.schedule,
	next_run_at=excluded.next_run_at, data=excluded.data`,
		a.ID, a.OwnerID, a.Name, a.WebhookSecret, a.ChatbotChannelFilter, a.Schedule, next, string(blob))
	if err != nil {
		return fmt.Errorf("personaStore.SaveAgent: %w", err)
	}
	return nil
}

// scanAgents unmarshals the `data` column of every row in rows.
func scanAgents(rows *sql.Rows) ([]*persona.Agent, error) {
	defer rows.Close()
	var out []*persona.Agent
	for rows.Next() {
		var blob string
		if err := rows.Scan(&blob); err != nil {
			return nil, err
		}
		var a persona.Agent
		if err := json.Unmarshal([]byte(blob), &a); err != nil {
			return nil, err
		}
		out = append(out, &a)
	}
	return out, rows.Err()
}

func (s *personaStore) getOne(ctx context.Context, where string, arg ...any) (*persona.Agent, error) {
	var blob string
	err := s.db.QueryRowContext(ctx, `SELECT data FROM agents WHERE `+where, arg...).Scan(&blob)
	switch {
	case errors.Is(err, sql.ErrNoRows):
		return nil, persona.ErrNotFound
	case err != nil:
		return nil, err
	}
	var a persona.Agent
	if err := json.Unmarshal([]byte(blob), &a); err != nil {
		return nil, err
	}
	return &a, nil
}

func (s *personaStore) GetAgent(ctx context.Context, id string) (*persona.Agent, error) {
	return s.getOne(ctx, "id = ?", id)
}

func (s *personaStore) GetAgentByName(ctx context.Context, ownerID, name string) (*persona.Agent, error) {
	return s.getOne(ctx, "owner_id = ? AND name = ?", ownerID, name)
}

func (s *personaStore) GetAgentByWebhookSecret(ctx context.Context, secret string) (*persona.Agent, error) {
	if secret == "" {
		return nil, persona.ErrNotFound
	}
	return s.getOne(ctx, "webhook_secret = ?", secret)
}

func (s *personaStore) ListAgents(ctx context.Context, ownerID string) ([]*persona.Agent, error) {
	rows, err := s.db.QueryContext(ctx, `SELECT data FROM agents WHERE owner_id = ? ORDER BY name`, ownerID)
	if err != nil {
		return nil, fmt.Errorf("personaStore.ListAgents: %w", err)
	}
	return scanAgents(rows)
}

func (s *personaStore) ListAllAgents(ctx context.Context) ([]*persona.Agent, error) {
	rows, err := s.db.QueryContext(ctx, `SELECT data FROM agents ORDER BY name`)
	if err != nil {
		return nil, fmt.Errorf("personaStore.ListAllAgents: %w", err)
	}
	return scanAgents(rows)
}

func (s *personaStore) DeleteAgent(ctx context.Context, id string) error {
	if _, err := s.db.ExecContext(ctx, `DELETE FROM agents WHERE id = ?`, id); err != nil {
		return fmt.Errorf("personaStore.DeleteAgent: %w", err)
	}
	return nil
}

func (s *personaStore) ListAgentsByChatbotChannelFilter(ctx context.Context) ([]*persona.Agent, error) {
	rows, err := s.db.QueryContext(ctx, `SELECT data FROM agents WHERE chatbot_channel_filter != '' ORDER BY name`)
	if err != nil {
		return nil, fmt.Errorf("personaStore.ListAgentsByChatbotChannelFilter: %w", err)
	}
	return scanAgents(rows)
}

func (s *personaStore) ListScheduledAgents(ctx context.Context, dueBefore time.Time) ([]*persona.Agent, error) {
	rows, err := s.db.QueryContext(ctx,
		`SELECT data FROM agents WHERE schedule != '' AND next_run_at > 0 AND next_run_at <= ? ORDER BY next_run_at`,
		dueBefore.Unix())
	if err != nil {
		return nil, fmt.Errorf("personaStore.ListScheduledAgents: %w", err)
	}
	return scanAgents(rows)
}

func (s *personaStore) MarkAgentScheduledRun(ctx context.Context, agentID string, ranAt, nextAt time.Time) error {
	// Single atomic statement, not Get→mutate→Save: closes the lost-update
	// window a concurrent Mark/edit would otherwise open. json_set keeps the
	// blob's *time.Time fields consistent with the next_run_at column (Go
	// encodes time.Time as RFC3339Nano, so it round-trips through GetAgent).
	res, err := s.db.ExecContext(ctx,
		`UPDATE agents SET next_run_at=?, data=json_set(data,'$.NextRunAt',?,'$.LastScheduledRunAt',?) WHERE id=?`,
		nextAt.Unix(), nextAt.Format(time.RFC3339Nano), ranAt.Format(time.RFC3339Nano), agentID)
	if err != nil {
		return fmt.Errorf("personaStore.MarkAgentScheduledRun: %w", err)
	}
	if n, _ := res.RowsAffected(); n == 0 {
		return persona.ErrNotFound
	}
	return nil
}