package authrequest

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

	"git.faercol.me/faercol/polyculeconnect/polyculeconnect/internal/model"
	"git.faercol.me/faercol/polyculeconnect/polyculeconnect/logger"
	"github.com/google/uuid"
)

var ErrNotFound = errors.New("backend not found")

const authRequestRows = `"id", "client_id", "backend_id", "scopes", "redirect_uri", "state", "nonce", "response_type", "creation_time", "done", "code_challenge", "code_challenge_method", "auth_time", "claim_user_id", "claim_username", "claim_email"`

type AuthRequestDB interface {
	GetAuthRequestByID(ctx context.Context, id uuid.UUID) (*model.AuthRequest, error)
	GetAuthRequestByUserID(ctx context.Context, id uuid.UUID) (*model.AuthRequest, error)
	CreateAuthRequest(ctx context.Context, req model.AuthRequest) error
	ValidateAuthRequest(ctx context.Context, reqID uuid.UUID, user *model.User) error
	DeleteAuthRequest(ctx context.Context, reqID uuid.UUID) error
}

type sqlAuthRequestDB struct {
	db *sql.DB
}

type dbUser struct {
	id       string
	username string
	email    string
}

func (db *sqlAuthRequestDB) GetAuthRequestByID(ctx context.Context, id uuid.UUID) (*model.AuthRequest, error) {
	logger.L.Debugf("Getting auth request with id %s", id)
	query := fmt.Sprintf(`SELECT %s FROM "auth_request_2" WHERE "id" = ?`, authRequestRows)
	row := db.db.QueryRowContext(ctx, query, id)

	var res model.AuthRequest
	var user dbUser
	var scopesStr []byte

	var timestamp *time.Time

	if err := row.Scan(&res.ID, &res.ClientID, &res.BackendID, &scopesStr, &res.RedirectURI, &res.State, &res.Nonce, &res.ResponseType, &res.CreationDate, &res.DoneVal, &res.CodeChallenge, &res.CodeChallengeMethod, &timestamp, &user.id, &user.username, &user.email); err != nil {
		return nil, fmt.Errorf("failed to get auth request from DB: %w", err)
	}
	if timestamp != nil {
		res.AuthTime = *timestamp
	}
	if user.id != "" {
		userID, err := uuid.Parse(user.id)
		if err != nil {
			return nil, fmt.Errorf("invalid format for user id: %w", err)
		}
		res.User = &model.User{
			ID:       userID,
			Username: user.username,
			Email:    user.email,
		}
	}
	if err := json.Unmarshal(scopesStr, &res.Scopes); err != nil {
		return nil, fmt.Errorf("invalid format for scopes: %w", err)
	}

	return &res, nil
}

func (db *sqlAuthRequestDB) GetAuthRequestByUserID(ctx context.Context, id uuid.UUID) (*model.AuthRequest, error) {
	logger.L.Debugf("Getting auth request with user id %s", id)
	query := fmt.Sprintf(`SELECT %s FROM "auth_request_2" WHERE "claim_user_id" = ?`, authRequestRows)
	row := db.db.QueryRowContext(ctx, query, id)

	var res model.AuthRequest
	var user dbUser
	var scopesStr []byte

	var timestamp *time.Time

	if err := row.Scan(&res.ID, &res.ClientID, &res.BackendID, &scopesStr, &res.RedirectURI, &res.State, &res.Nonce, &res.ResponseType, &res.CreationDate, &res.DoneVal, &res.CodeChallenge, &res.CodeChallengeMethod, &timestamp, &user.id, &user.username, &user.email); err != nil {
		return nil, fmt.Errorf("failed to get auth request from DB: %w", err)
	}
	if timestamp != nil {
		res.AuthTime = *timestamp
	}
	if user.id != "" {
		userID, err := uuid.Parse(user.id)
		if err != nil {
			return nil, fmt.Errorf("invalid format for user id: %w", err)
		}
		res.User = &model.User{
			ID:       userID,
			Username: user.username,
			Email:    user.email,
		}
	}
	if err := json.Unmarshal(scopesStr, &res.Scopes); err != nil {
		return nil, fmt.Errorf("invalid format for scopes: %w", err)
	}

	return &res, nil
}

func (db *sqlAuthRequestDB) CreateAuthRequest(ctx context.Context, req model.AuthRequest) error {
	logger.L.Debugf("Creating a new auth request between client app %s and backend %s", req.ClientID, req.BackendID)
	tx, err := db.db.BeginTx(ctx, nil)
	if err != nil {
		return fmt.Errorf("failed to start transaction: %w", err)
	}
	defer func() { _ = tx.Rollback() }()

	scopesStr, err := json.Marshal(req.Scopes)
	if err != nil {
		return fmt.Errorf("failed to serialize scopes: %w", err)
	}

	// TODO: when the old table is done, rename into auth_request
	query := fmt.Sprintf(`INSERT INTO "auth_request_2" (%s) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, NULL, '', '', '')`, authRequestRows)
	_, err = tx.ExecContext(ctx, query,
		req.ID, req.ClientID, req.BackendID,
		scopesStr, req.RedirectURI, req.State,
		req.Nonce, req.ResponseType, req.CreationDate, false,
		req.CodeChallenge, req.CodeChallengeMethod,
	)
	if err != nil {
		return fmt.Errorf("failed to insert in DB: %w", err)
	}

	if err := tx.Commit(); err != nil {
		return fmt.Errorf("failed to commit transaction: %w", err)
	}

	return nil
}

func (db *sqlAuthRequestDB) ValidateAuthRequest(ctx context.Context, reqID uuid.UUID, user *model.User) error {
	logger.L.Debugf("Validating auth request %s", reqID)
	tx, err := db.db.BeginTx(ctx, nil)
	if err != nil {
		return fmt.Errorf("failed to start transaction: %w", err)
	}
	defer func() { _ = tx.Rollback() }()

	res, err := tx.ExecContext(ctx, `UPDATE "auth_request_2" SET done = true, auth_time = $1, claim_user_id = $2, claim_username = $3, claim_email = $4 WHERE id = $5`, time.Now().UTC(), user.ID, user.Username, user.Email, reqID.String())
	if err != nil {
		return fmt.Errorf("failed to update in DB: %w", err)
	}
	affectedRows, err := res.RowsAffected()
	if err != nil {
		return fmt.Errorf("failed to check number of affected rows: %w", err)
	}
	if affectedRows != 1 {
		return ErrNotFound
	}

	if err := tx.Commit(); err != nil {
		return fmt.Errorf("failed to commit transaction: %w", err)
	}

	return nil
}

func (db *sqlAuthRequestDB) DeleteAuthRequest(ctx context.Context, reqID uuid.UUID) error {
	logger.L.Debugf("Deleting auth request: %s", reqID)
	tx, err := db.db.BeginTx(ctx, nil)
	if err != nil {
		return fmt.Errorf("failed to start transaction: %w", err)
	}
	defer func() { _ = tx.Rollback() }()

	_, err = tx.ExecContext(ctx, `DELETE FROM "auth_request_2" WHERE id = $1`, reqID.String())
	if err != nil {
		return fmt.Errorf("failed to delete auth request: %w", err)
	}
	if err := tx.Commit(); err != nil {
		return fmt.Errorf("failed to commit transaction: %w", err)
	}
	return nil
}

func New(db *sql.DB) *sqlAuthRequestDB {
	return &sqlAuthRequestDB{db: db}
}