package website

import (
	"errors"
	"net/http"
	"time"

	"git.handmade.network/hmn/hmn/src/config"
	"git.handmade.network/hmn/hmn/src/db"
	"git.handmade.network/hmn/hmn/src/discord"
	"git.handmade.network/hmn/hmn/src/hmnurl"
	"git.handmade.network/hmn/hmn/src/models"
	"git.handmade.network/hmn/hmn/src/oops"
)

func DiscordOAuthCallback(c *RequestContext) ResponseData {
	query := c.Req.URL.Query()

	// Check the state
	state := query.Get("state")
	if state != c.CurrentSession.CSRFToken {
		// CSRF'd!!!!

		c.Logger.Warn().Str("userId", c.CurrentUser.Username).Msg("user failed Discord OAuth state validation - potential attack?")

		res := c.Redirect("/", http.StatusSeeOther)
		logoutUser(c, &res)

		return res
	}

	// Check for error values and redirect back to user settings
	if errCode := query.Get("error"); errCode != "" {
		if errCode == "access_denied" {
			// This occurs when the user cancels. Just go back to the profile page.
			return c.Redirect(hmnurl.BuildUserSettings("discord"), http.StatusSeeOther)
		} else {
			return RejectRequest(c, "Failed to authenticate with Discord.")
		}
	}

	// Do the actual token exchange
	code := query.Get("code")
	res, err := discord.ExchangeOAuthCode(c.Context(), code, hmnurl.BuildDiscordOAuthCallback())
	if err != nil {
		return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to exchange Discord authorization code"))
	}
	expiry := time.Now().Add(time.Duration(res.ExpiresIn) * time.Second)

	user, err := discord.GetCurrentUserAsOAuth(c.Context(), res.AccessToken)
	if err != nil {
		return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to fetch Discord user info"))
	}

	// Add the role on Discord
	err = discord.AddGuildMemberRole(c.Context(), user.ID, config.Config.Discord.MemberRoleID)
	if err != nil {
		return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to add member role"))
	}

	// Add the user to our database
	_, err = c.Conn.Exec(c.Context(),
		`
		INSERT INTO handmade_discorduser (username, discriminator, access_token, refresh_token, avatar, locale, userid, expiry, hmn_user_id)
		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
		`,
		user.Username,
		user.Discriminator,
		res.AccessToken,
		res.RefreshToken,
		user.Avatar,
		user.Locale,
		user.ID,
		expiry,
		c.CurrentUser.ID,
	)
	if err != nil {
		return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to save new Discord user info"))
	}

	if c.CurrentUser.Status == models.UserStatusConfirmed {
		_, err = c.Conn.Exec(c.Context(),
			`
			UPDATE auth_user
			SET status = $1
			WHERE id = $2
			`,
			models.UserStatusApproved,
			c.CurrentUser.ID,
		)
		if err != nil {
			c.Logger.Error().Err(err).Msg("failed to set user status to approved after linking discord account")
			// NOTE(asaf): It's not worth failing the request over this, so we're not returning an error to the user.
		}
	}

	return c.Redirect(hmnurl.BuildUserSettings("discord"), http.StatusSeeOther)
}

func DiscordUnlink(c *RequestContext) ResponseData {
	tx, err := c.Conn.Begin(c.Context())
	if err != nil {
		panic(err)
	}
	defer tx.Rollback(c.Context())

	discordUser, err := db.QueryOne[models.DiscordUser](c.Context(), tx,
		`
		SELECT $columns
		FROM handmade_discorduser
		WHERE hmn_user_id = $1
		`,
		c.CurrentUser.ID,
	)
	if err != nil {
		if errors.Is(err, db.NotFound) {
			return c.Redirect(hmnurl.BuildUserSettings("discord"), http.StatusSeeOther)
		} else {
			return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to get Discord user for unlink"))
		}
	}

	_, err = tx.Exec(c.Context(),
		`
		DELETE FROM handmade_discorduser
		WHERE id = $1
		`,
		discordUser.ID,
	)
	if err != nil {
		return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to delete Discord user"))
	}

	err = tx.Commit(c.Context())
	if err != nil {
		return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to commit Discord user delete"))
	}

	err = discord.RemoveGuildMemberRole(c.Context(), discordUser.UserID, config.Config.Discord.MemberRoleID)
	if err != nil {
		c.Logger.Warn().Err(err).Msg("failed to remove member role on unlink")
	}

	return c.Redirect(hmnurl.BuildUserSettings("discord"), http.StatusSeeOther)
}

func DiscordShowcaseBacklog(c *RequestContext) ResponseData {
	duser, err := db.QueryOne[models.DiscordUser](c.Context(), c.Conn,
		`SELECT $columns FROM handmade_discorduser WHERE hmn_user_id = $1`,
		c.CurrentUser.ID,
	)
	if errors.Is(err, db.NotFound) {
		// Nothing to do
		c.Logger.Warn().Msg("could not do showcase backlog because no discord user exists")
		return c.Redirect(hmnurl.BuildUserProfile(c.CurrentUser.Username), http.StatusSeeOther)
	} else if err != nil {
		return c.ErrorResponse(http.StatusInternalServerError, oops.New(err, "failed to get discord user"))
	}

	msgIDs, err := db.QueryScalar[string](c.Context(), c.Conn,
		`
		SELECT msg.id
		FROM
			handmade_discordmessage AS msg
		WHERE
			msg.user_id = $1
			AND msg.channel_id = $2
		`,
		duser.UserID,
		config.Config.Discord.ShowcaseChannelID,
	)
	if err != nil {
		return c.ErrorResponse(http.StatusInternalServerError, err)
	}

	for _, msgID := range msgIDs {
		interned, err := discord.FetchInternedMessage(c.Context(), c.Conn, msgID)
		if err != nil && !errors.Is(err, db.NotFound) {
			return c.ErrorResponse(http.StatusInternalServerError, err)
		} else if err == nil {
			// NOTE(asaf): Creating snippet even if the checkbox is off because the user asked us to.
			err = discord.HandleSnippetForInternedMessage(c.Context(), c.Conn, interned, true)
			if err != nil {
				return c.ErrorResponse(http.StatusInternalServerError, err)
			}
		}
	}

	return c.Redirect(hmnurl.BuildUserProfile(c.CurrentUser.Username), http.StatusSeeOther)
}