package model

import (
	"database/sql"
	"errors"
	"fmt"
	"log/slog"
	"time"
)

type Snippet struct {
	ID int
	// Title     string
	// Content   string
	Title     sql.NullString
	Content   sql.NullString
	CreatedAt time.Time
	UpdatedAt time.Time
	ExpiresAt time.Time
}

func (s *Snippet) GetTitle() {
	return
}

type SnippetServiceInterface interface {
	Insert(title, content string, expiresAt int) (int, error)
	Get(id int) (Snippet, error)
	Lastest() ([]Snippet, error)
}

type SnippetService struct {
	DB *sql.DB
}

// Insert inserts a new SnippetModel into the database
func (s *SnippetService) Insert(title, content string, expiresAt int) (int, error) {
	slog.Debug(fmt.Sprintf("Inserting new snippet. Title: %s", title))
	// Really don't prepare statements. There are a lot of gotcha's where they exist on the connection objects they were created. They can potentially
	// recreate connections. It's an optimization you probably don't need at the moment.
	stmt, err := s.DB.Prepare("INSERT INTO snippets (title, content, expires_at) VALUES ($1, $2, DATETIME(CURRENT_TIMESTAMP, '+' || $3 || ' DAY'))")
	if err != nil {
		slog.Debug("The prepared statement has an error")
		return 0, err
	}
	defer stmt.Close()

	// stmt.Exec returns a sql.Result. That also has access to the statement metadata
	// use _ if you don't care about the result and only want to check the err.

	// Exec will NOT reserve a connection. unlike db.Query which returns a sql.Rows that
	// will hold on to a connection until .Close() is called.
	res, err := stmt.Exec(title, content, expiresAt)
	if err != nil {
		slog.Debug("SQL DML statement returned an error.")
		return 0, err
	}

	// Use the LastInsertId() method on the result to get the ID of our
	// newly inserted record in the snippets table.
	lastId, err := res.LastInsertId()
	if err != nil {
		slog.Debug("An error occured when retrieving insert result id.")
		return 0, err
	}

	// The ID returned has the type int64, so we convert it to an int type
	// before returning.
	slog.Debug(fmt.Sprintf("Inserted new snippet. Snippet pk: %d", int(lastId)))
	return int(lastId), nil
}

// Get retrieves a specific Snippet by ID ignoring the record if expired.
func (s *SnippetService) Get(id int) (Snippet, error) {

	stmt := `SELECT id, title, content, created_at, updated_at, expires_at FROM snippets 
	WHERE expires_at > CURRENT_TIMESTAMP AND id = $1`

	// errors from DB.QueryRow() are deferred until Scan() is called.
	// meaning you could also have used DB.QueryRow(...).Scan(...)
	row := s.DB.QueryRow(stmt, id)

	var snip Snippet

	err := row.Scan(&snip.ID,
		&snip.Title,
		&snip.Content,
		&snip.CreatedAt,
		&snip.UpdatedAt,
		&snip.ExpiresAt,
	)

	if err != nil {
		slog.Debug("SQL DML statement returned an error.")
		// Loop up the difference between errors.Is and errors.As
		if errors.Is(err, sql.ErrNoRows) {
			return Snippet{}, ErrNoRecord
		} else {
			return Snippet{}, err
		}
	}

	return snip, nil
}

// Latest retrieves up to latest 10 Snippets from the database.
func (s *SnippetService) Lastest() ([]Snippet, error) {

	stmt := `SELECT id, title, content, created_at, updated_at, expires_at FROM snippets
	WHERE expires_at > CURRENT_TIMESTAMP ORDER BY id DESC LIMIT 10`

	rows, err := s.DB.Query(stmt)
	if err != nil {
		return nil, err
	}

	// We defer rows.Close() to ensure the sql.Rows resultset is
	// always properly closed before the Latest() method returns. This defer
	// statement should come *after* you check for an error from the Query()
	// method. Otherwise, if Query() returns an error, you'll get a panic
	// trying to close a nil resultset.
	defer rows.Close()

	var snippets []Snippet

	// Use rows.Next to iterate through the rows in the resultset. This
	// prepares the first (and then each subsequent) row to be acted on by the
	// rows.Scan() method. If iteration over all the rows completes then the
	// resultset automatically closes itself and frees-up the underlying
	// database connection.
	for rows.Next() {
		var snip Snippet

		err := rows.Scan(&snip.ID,
			&snip.Title,
			&snip.Content,
			&snip.CreatedAt,
			&snip.UpdatedAt,
			&snip.ExpiresAt,
		)
		if err != nil {
			return nil, err
		}

		snippets = append(snippets, snip)
	}

	// When the rows.Next() loop has finished we call rows.Err() to retrieve any
	// error that was encountered during the iteration. It's important to
	// call this - don't assume that a successful iteration was completed
	// over the whole resultset.
	if err = rows.Err(); err != nil {
		return nil, err
	}

	return snippets, nil
}