package api

import (
	"context"
	"net/http"
	"time"

	"github.com/danielgtaylor/huma/v2"
	"github.com/google/uuid"
	"github.com/jackc/pgx/v5/pgtype"

	"completed/internal/auth"
	"completed/internal/db"
	"completed/internal/model"
)

type authOutput struct {
	SetCookie string `header:"Set-Cookie"`
	Body      model.AuthResponse
}

// sessionCookie builds the Set-Cookie value for a successful login. Secure
// is left unset because the app is also meant to run over plain HTTP in
// local/docker-compose use; put a TLS-terminating proxy in front for
// anything reachable over the network and set Secure there instead.
func sessionCookie(token string) string {
	c := http.Cookie{
		Name:     sessionCookieName,
		Value:    token,
		Path:     "/",
		HttpOnly: true,
		SameSite: http.SameSiteLaxMode,
		MaxAge:   auth.SessionDuration,
	}
	return c.String()
}

func clearedSessionCookie() string {
	c := http.Cookie{
		Name:     sessionCookieName,
		Value:    "",
		Path:     "/",
		HttpOnly: true,
		SameSite: http.SameSiteLaxMode,
		MaxAge:   -1,
	}
	return c.String()
}

// newSession creates and stores a session for userID, returning the token
// to hand back to the client (only its hash is ever persisted).
func newSession(ctx context.Context, queries db.Querier, userID uuid.UUID) (string, error) {
	token, tokenHash, err := auth.NewSessionToken()
	if err != nil {
		return "", err
	}
	err = queries.CreateSession(ctx, db.CreateSessionParams{
		TokenHash: tokenHash,
		UserID:    userID,
		ExpiresAt: pgtype.Timestamptz{Time: time.Now().Add(auth.SessionDuration * time.Second), Valid: true},
	})
	return token, err
}

func registerAuthRoutes(api huma.API, queries db.Querier) {
	huma.Register(api, huma.Operation{
		OperationID: "register",
		Tags:        []string{"Auth"},
		Method:      http.MethodPost,
		Path:        "/api/auth/register",
		Summary:     "Register a new account",
	}, func(ctx context.Context, input *struct{ Body model.RegisterInput }) (*authOutput, error) {
		hash, err := auth.HashPassword(input.Body.Password)
		if err != nil {
			return nil, huma.Error500InternalServerError("could not process password")
		}

		u, err := queries.CreateUser(ctx, db.CreateUserParams{
			Email:        input.Body.Email,
			PasswordHash: hash,
			Name:         input.Body.Name,
			Bio:          pgtype.Text{},
		})
		if err != nil {
			return nil, dbError(err)
		}

		token, err := newSession(ctx, queries, u.ID)
		if err != nil {
			return nil, huma.Error500InternalServerError("could not create session")
		}

		return &authOutput{
			SetCookie: sessionCookie(token),
			Body: model.AuthResponse{
				Token: token,
				User:  model.User{ID: u.ID.String(), Email: u.Email, Name: u.Name, IsAdmin: u.IsAdmin},
			},
		}, nil
	})

	huma.Register(api, huma.Operation{
		OperationID: "login",
		Tags:        []string{"Auth"},
		Method:      http.MethodPost,
		Path:        "/api/auth/login",
		Summary:     "Log in to an existing account",
	}, func(ctx context.Context, input *struct{ Body model.LoginInput }) (*authOutput, error) {
		u, err := queries.GetUserByEmail(ctx, input.Body.Email)
		if err != nil {
			// Same message whether the email is unknown or the password is
			// wrong, so a client can't use this endpoint to enumerate
			// registered emails.
			return nil, huma.Error401Unauthorized("invalid email or password")
		}

		ok, err := auth.VerifyPassword(input.Body.Password, u.PasswordHash)
		if err != nil || !ok {
			return nil, huma.Error401Unauthorized("invalid email or password")
		}

		token, err := newSession(ctx, queries, u.ID)
		if err != nil {
			return nil, huma.Error500InternalServerError("could not create session")
		}

		return &authOutput{
			SetCookie: sessionCookie(token),
			Body: model.AuthResponse{
				Token: token,
				User:  model.User{ID: u.ID.String(), Email: u.Email, Name: u.Name, IsAdmin: u.IsAdmin},
			},
		}, nil
	})

	logoutOp := huma.Operation{
		OperationID: "logout",
		Tags:        []string{"Auth"},
		Method:      http.MethodPost,
		Path:        "/api/auth/logout",
		Summary:     "Log out of the current session",
	}
	addAuth(&logoutOp, api, queries)
	huma.Register(api, logoutOp, func(ctx context.Context, input *struct{}) (*struct {
		SetCookie string `header:"Set-Cookie"`
	}, error) {
		_ = queries.DeleteSession(ctx, auth.HashSessionToken(tokenFromContext(ctx)))
		return &struct {
			SetCookie string `header:"Set-Cookie"`
		}{SetCookie: clearedSessionCookie()}, nil
	})

	meOp := huma.Operation{
		OperationID: "get-me",
		Tags:        []string{"Auth"},
		Method:      http.MethodGet,
		Path:        "/api/auth/me",
		Summary:     "Get the current user",
	}
	addAuth(&meOp, api, queries)
	huma.Register(api, meOp, func(ctx context.Context, input *struct{}) (*struct{ Body model.User }, error) {
		return &struct{ Body model.User }{Body: userFromContext(ctx).toModel()}, nil
	})
}