package registry

import (
	"database/sql"
	"fmt"
	"time"
)

// Component represents a component in the registry.
type Component struct {
	Name          string
	Service       string
	Image         string
	Network       string
	UserSpec      string
	Restart       string
	DesiredState  string
	ObservedState string
	Version       string
	Ports         []string
	Volumes       []string
	Cmd           []string
	CreatedAt     time.Time
	UpdatedAt     time.Time
}

// CreateComponent creates a new component in the registry.
func CreateComponent(db *sql.DB, c *Component) error {
	tx, err := db.Begin()
	if err != nil {
		return fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback() //nolint:errcheck

	_, err = tx.Exec(`
		INSERT INTO components (name, service, image, network, user_spec, restart, desired_state, observed_state, version)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)`,
		c.Name, c.Service, c.Image, c.Network, c.UserSpec, c.Restart,
		c.DesiredState, c.ObservedState, c.Version,
	)
	if err != nil {
		return fmt.Errorf("insert component %q/%q: %w", c.Service, c.Name, err)
	}

	if err := setPorts(tx, c.Service, c.Name, c.Ports); err != nil {
		return err
	}
	if err := setVolumes(tx, c.Service, c.Name, c.Volumes); err != nil {
		return err
	}
	if err := setCmd(tx, c.Service, c.Name, c.Cmd); err != nil {
		return err
	}

	return tx.Commit()
}

// GetComponent retrieves a component by service and name.
func GetComponent(db *sql.DB, service, name string) (*Component, error) {
	c := &Component{}
	var createdAt, updatedAt string
	err := db.QueryRow(`
		SELECT name, service, image, network, user_spec, restart,
		       desired_state, observed_state, version, created_at, updated_at
		FROM components WHERE service = ? AND name = ?`,
		service, name,
	).Scan(&c.Name, &c.Service, &c.Image, &c.Network, &c.UserSpec, &c.Restart,
		&c.DesiredState, &c.ObservedState, &c.Version, &createdAt, &updatedAt)
	if err != nil {
		return nil, fmt.Errorf("get component %q/%q: %w", service, name, err)
	}
	c.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
	c.UpdatedAt, _ = time.Parse("2006-01-02 15:04:05", updatedAt)

	c.Ports, err = getPorts(db, service, name)
	if err != nil {
		return nil, err
	}
	c.Volumes, err = getVolumes(db, service, name)
	if err != nil {
		return nil, err
	}
	c.Cmd, err = getCmd(db, service, name)
	if err != nil {
		return nil, err
	}

	return c, nil
}

// ListComponents returns all components for a service.
func ListComponents(db *sql.DB, service string) ([]Component, error) {
	rows, err := db.Query(`
		SELECT name, service, image, network, user_spec, restart,
		       desired_state, observed_state, version, created_at, updated_at
		FROM components WHERE service = ? ORDER BY name`,
		service,
	)
	if err != nil {
		return nil, fmt.Errorf("list components for %q: %w", service, err)
	}
	defer func() { _ = rows.Close() }()

	var components []Component
	for rows.Next() {
		var c Component
		var createdAt, updatedAt string
		if err := rows.Scan(&c.Name, &c.Service, &c.Image, &c.Network, &c.UserSpec, &c.Restart,
			&c.DesiredState, &c.ObservedState, &c.Version, &createdAt, &updatedAt); err != nil {
			return nil, fmt.Errorf("scan component: %w", err)
		}
		c.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
		c.UpdatedAt, _ = time.Parse("2006-01-02 15:04:05", updatedAt)

		c.Ports, _ = getPorts(db, c.Service, c.Name)
		c.Volumes, _ = getVolumes(db, c.Service, c.Name)
		c.Cmd, _ = getCmd(db, c.Service, c.Name)

		components = append(components, c)
	}
	return components, rows.Err()
}

// UpdateComponentState updates desired and/or observed state.
func UpdateComponentState(db *sql.DB, service, name, desiredState, observedState string) error {
	res, err := db.Exec(`
		UPDATE components
		SET desired_state = CASE WHEN ? = '' THEN desired_state ELSE ? END,
		    observed_state = CASE WHEN ? = '' THEN observed_state ELSE ? END,
		    updated_at = datetime('now')
		WHERE service = ? AND name = ?`,
		desiredState, desiredState, observedState, observedState, service, name,
	)
	if err != nil {
		return fmt.Errorf("update state %q/%q: %w", service, name, err)
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return fmt.Errorf("update state %q/%q: %w", service, name, sql.ErrNoRows)
	}
	return nil
}

// UpdateComponentSpec updates the full spec for an existing component.
func UpdateComponentSpec(db *sql.DB, c *Component) error {
	tx, err := db.Begin()
	if err != nil {
		return fmt.Errorf("begin tx: %w", err)
	}
	defer tx.Rollback() //nolint:errcheck

	_, err = tx.Exec(`
		UPDATE components
		SET image = ?, network = ?, user_spec = ?, restart = ?, version = ?, updated_at = datetime('now')
		WHERE service = ? AND name = ?`,
		c.Image, c.Network, c.UserSpec, c.Restart, c.Version, c.Service, c.Name,
	)
	if err != nil {
		return fmt.Errorf("update component %q/%q: %w", c.Service, c.Name, err)
	}

	if err := setPorts(tx, c.Service, c.Name, c.Ports); err != nil {
		return err
	}
	if err := setVolumes(tx, c.Service, c.Name, c.Volumes); err != nil {
		return err
	}
	if err := setCmd(tx, c.Service, c.Name, c.Cmd); err != nil {
		return err
	}

	return tx.Commit()
}

// DeleteComponent removes a component.
func DeleteComponent(db *sql.DB, service, name string) error {
	res, err := db.Exec("DELETE FROM components WHERE service = ? AND name = ?", service, name)
	if err != nil {
		return fmt.Errorf("delete component %q/%q: %w", service, name, err)
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return fmt.Errorf("delete component %q/%q: %w", service, name, sql.ErrNoRows)
	}
	return nil
}

// helper: set port mappings (delete + re-insert)
func setPorts(tx *sql.Tx, service, component string, ports []string) error {
	if _, err := tx.Exec("DELETE FROM component_ports WHERE service = ? AND component = ?", service, component); err != nil {
		return fmt.Errorf("clear ports %q/%q: %w", service, component, err)
	}
	for _, p := range ports {
		if _, err := tx.Exec("INSERT INTO component_ports (service, component, mapping) VALUES (?, ?, ?)", service, component, p); err != nil {
			return fmt.Errorf("insert port %q/%q %q: %w", service, component, p, err)
		}
	}
	return nil
}

func getPorts(db *sql.DB, service, component string) ([]string, error) {
	rows, err := db.Query("SELECT mapping FROM component_ports WHERE service = ? AND component = ? ORDER BY mapping", service, component)
	if err != nil {
		return nil, fmt.Errorf("get ports %q/%q: %w", service, component, err)
	}
	defer func() { _ = rows.Close() }()
	var ports []string
	for rows.Next() {
		var p string
		if err := rows.Scan(&p); err != nil {
			return nil, err
		}
		ports = append(ports, p)
	}
	return ports, rows.Err()
}

// helper: set volume mappings
func setVolumes(tx *sql.Tx, service, component string, volumes []string) error {
	if _, err := tx.Exec("DELETE FROM component_volumes WHERE service = ? AND component = ?", service, component); err != nil {
		return fmt.Errorf("clear volumes %q/%q: %w", service, component, err)
	}
	for _, v := range volumes {
		if _, err := tx.Exec("INSERT INTO component_volumes (service, component, mapping) VALUES (?, ?, ?)", service, component, v); err != nil {
			return fmt.Errorf("insert volume %q/%q %q: %w", service, component, v, err)
		}
	}
	return nil
}

func getVolumes(db *sql.DB, service, component string) ([]string, error) {
	rows, err := db.Query("SELECT mapping FROM component_volumes WHERE service = ? AND component = ? ORDER BY mapping", service, component)
	if err != nil {
		return nil, fmt.Errorf("get volumes %q/%q: %w", service, component, err)
	}
	defer func() { _ = rows.Close() }()
	var volumes []string
	for rows.Next() {
		var v string
		if err := rows.Scan(&v); err != nil {
			return nil, err
		}
		volumes = append(volumes, v)
	}
	return volumes, rows.Err()
}

// helper: set command args
func setCmd(tx *sql.Tx, service, component string, cmd []string) error {
	if _, err := tx.Exec("DELETE FROM component_cmd WHERE service = ? AND component = ?", service, component); err != nil {
		return fmt.Errorf("clear cmd %q/%q: %w", service, component, err)
	}
	for i, arg := range cmd {
		if _, err := tx.Exec("INSERT INTO component_cmd (service, component, position, arg) VALUES (?, ?, ?, ?)", service, component, i, arg); err != nil {
			return fmt.Errorf("insert cmd %q/%q [%d]: %w", service, component, i, err)
		}
	}
	return nil
}

func getCmd(db *sql.DB, service, component string) ([]string, error) {
	rows, err := db.Query("SELECT arg FROM component_cmd WHERE service = ? AND component = ? ORDER BY position", service, component)
	if err != nil {
		return nil, fmt.Errorf("get cmd %q/%q: %w", service, component, err)
	}
	defer func() { _ = rows.Close() }()
	var cmd []string
	for rows.Next() {
		var arg string
		if err := rows.Scan(&arg); err != nil {
			return nil, err
		}
		cmd = append(cmd, arg)
	}
	return cmd, rows.Err()
}