import * as crypto from 'crypto';

import * as pg from 'pg';

import * as uuid from 'uuid';

import ConcurrentQueue from '../concurrent-queue/concurrent-queue';
import Logger from '../logger/logger';

const LOG = Logger.create('db');

const db = new pg.Client({
    host: 'localhost',
    user: 'cordis',
    password: 'cordis_pass',
    database: 'cordis',
});

export default class DB {
    static async connect(): Promise<void> {
        await db.connect();
    }

    static async end(): Promise<void> {
        await db.end();
    }

    private static TRANSACTION_QUEUE = new ConcurrentQueue<void>(1);

    static async beginTransaction(): Promise<void> {
        await db.query('BEGIN');
    }

    static async rollbackTransaction(): Promise<void> {
        await db.query('ROLLBACK');
    }

    static async commitTransaction(): Promise<void> {
        await db.query('COMMIT');
    }

    static async queueTransaction(func): Promise<void> {
        await DB.TRANSACTION_QUEUE.push(async () => {
            try {
                await this.beginTransaction();
                await func();
                await this.commitTransaction();
            } catch (e) {
                await this.rollbackTransaction();
                throw e;
            }
        });
    }

    static async getAllGuilds(): Promise<any[]> {
        let result = await db.query('SELECT * FROM "guilds" LEFT JOIN "guilds_meta" ON "guilds"."id"="guilds_meta"."id"');
        return result.rows;
    }

    // Returns the member_id and guild_id for the member with specified public key
    static async getMemberInfo(publicKey: crypto.KeyObject): Promise<any> {
        let der = publicKey.export({ type: 'spki', format: 'der' });

        LOG.silly(`searching for public key (der hash: ${LOG.inspect(crypto.createHash('sha256').update(der).digest().toString('hex'))})`);
    
        let result = await db.query('SELECT "id" AS member_id, "guild_id" FROM "members" WHERE "public_key"=$1', [ der ]);
    
        if (result.rows.length != 1) {
            throw new Error('unable to find member with specified public key');
        }
    
        return result.rows[0];
    }

    static async getGuild(guildId: string): Promise<any> {
        let result = await db.query('SELECT "name", "icon_resource_id" FROM "guilds_meta" WHERE "id"=$1', [ guildId ]);
        if (result.rows.length != 1) {
            throw new Error('unable to find guild with specified id');
        }
        return result.rows[0];
    }

    static async setName(guildId: string, name: string): Promise<any> {
        let result = await db.query(`
            UPDATE "guilds_meta" SET "name"=$1 WHERE "id"=$2
            RETURNING "name", "icon_resource_id"
        `, [ name, guildId ]);
        if (result.rows.length != 1) {
            throw new Error('unable to update guild name');
        }
        return result.rows[0];
    }

    static async setIcon(guildId: string, iconResourceId: string): Promise<any> {
        let result = await db.query(`
            UPDATE "guilds_meta" SET "icon_resource_id"=$1 WHERE "id"=$2
            RETURNING "name", "icon_resource_id"
        `, [ iconResourceId, guildId ]);
        if (result.rows.length != 1) {
            throw new Error('unable to update guild icon');
        }
        return result.rows[0];
    }

    static async getMembers(guildId: string): Promise<any[]> {
        let result = await db.query('SELECT * FROM "members_with_roles" WHERE "guild_id"=$1', [ guildId ]);
        return result.rows;
    }

    static async getMember(guildId: string, memberId: string): Promise<any> {
        let result = await db.query('SELECT * FROM "members_with_roles" WHERE "guild_id"=$1 AND "id"=$2', [ guildId, memberId ]);
        if (result.rows.length != 1) {
            throw new Error('unable to get member');
        }
        return result.rows[0];
    }

    static async getChannels(guildId: string): Promise<any[]> {
        let result = await db.query('SELECT "id", "index", "name", "flavor_text" FROM "channels" WHERE "guild_id"=$1 ORDER BY "index"', [ guildId ]);
        return result.rows;
    }

    static async createChannel(guildId: string, name: string, flavorText: string): Promise<any> {
        let channel = null;
        await DB.queueTransaction(async () => {
            let indexResult = await db.query('SELECT MAX("index") AS max_index FROM "channels" WHERE "guild_id"=$1', [ guildId ]);
            if (indexResult.rows.length != 1) {
                throw new Error('invalid index result');
            }
            let newIndex = (indexResult.rows[0].max_index || 0) + 1;
            let insertResult = await db.query(`
                INSERT INTO "channels" ("guild_id", "index", "name", "flavor_text")
                VALUES ($1, $2, $3, $4)
                RETURNING "id", "index", "name", "flavor_text"
            `, [ guildId, newIndex, name, flavorText ]);
            if (insertResult.rows.length != 1) {
                throw new Error('unable to insert channel');
            }
            channel = insertResult.rows[0];
        });
        return channel;
    }

    static async updateChannel(guildId: string, channelId: string, name: string, flavorText: string): Promise<any> {
        let result = await db.query(`
            UPDATE "channels" SET "name"=$1, "flavor_text"=$2 WHERE "guild_id"=$3 AND "id"=$4
            RETURNING *
        `, [ name, flavorText, guildId, channelId ]);
        if (result.rows.length != 1) {
            throw new Error('unable to update channel');
        }
        return result.rows[0];
    }

    static async getMessagesRecent(guildId: string, channelId: string, number: string): Promise<any> {
        let result = await db.query(`
        SELECT * FROM (
            SELECT
                "id", "channel_id", "member_id"
                ,"sent_dtg", "text"
                , "resource_id"
                , "resource_name"
                , "resource_width"
                , "resource_height"
                , "resource_preview_id"
                , "order"
            FROM "messages"
            WHERE "guild_id"=$1 AND "channel_id"=$2
            ORDER BY "order" DESC
            LIMIT $3
        ) AS "r" ORDER BY "r"."order" ASC`, [ guildId, channelId, number ]);
        return result.rows;
    }

    static async getMessagesBefore(guildId: string, channelId: string, messageId: string, number: number): Promise<any[]> {
        let result = await db.query(`
            SELECT * FROM (
                SELECT
                    "id", "channel_id", "member_id"
                    , "sent_dtg", "text"
                    , "resource_id"
                    , "resource_name"
                    , "resource_width"
                    , "resource_height"
                    , "resource_preview_id"
                    , "order"
                FROM "messages"
                WHERE
                    "guild_id"=$1
                    AND "channel_id"=$2
                    AND "order" < (SELECT "order" FROM "messages" WHERE "id"=$3)
                ORDER BY "order" DESC
                LIMIT $4
            ) AS "r" ORDER BY "r"."order" ASC`, [ guildId, channelId, messageId, number ]);
        return result.rows;
    }

    static async getMessagesAfter(guildId: string, channelId: string, messageId: string, number: number): Promise<any[]> {
        let result = await db.query(`
            SELECT
                "id", "channel_id", "member_id"
                , "sent_dtg", "text"
                , "resource_id"
                , "resource_name"
                , "resource_width"
                , "resource_height"
                , "resource_preview_id"
                , "order"
            FROM "messages"
            WHERE
                "guild_id"=$1
                AND "channel_id"=$2
                AND "order" > (SELECT "order" FROM "messages" WHERE "id"=$3)
            ORDER BY "order" ASC, "id" ASC
            LIMIT $4`, [ guildId, channelId, messageId, number ]);
        return result.rows;
    }

    static async getResource(guildId: string, resourceId: string): Promise<any> {
        let result = await db.query(`
            SELECT
                "id", "guild_id", "hash", "data"
            FROM
                "resources"
            WHERE
                "guild_id"=$1    
                AND "id"=$2
                
        `, [ guildId, resourceId ]);
        if (result.rows.length != 1) {
            throw new Error(`unable to find specified resource g#${guildId}, r#${resourceId}`);
        }
        return result.rows[0];
    }

    static async insertMessage(guildId: string, channelId: string, memberId: string, text: string): Promise<any> {
        let id = uuid.v4();
        let result = await db.query(
            `INSERT INTO "messages" (
                "id", "guild_id", "channel_id", "member_id", "text", "sent_dtg", "order"
            ) VALUES ($1::UUID, $2, $3, $4, $5, NOW(), LPAD(FLOOR(EXTRACT(epoch FROM NOW())::decimal * 100000)::text, 20, '0') || $1::text)
            RETURNING
                "id", "channel_id", "member_id"
                , "text", "sent_dtg"
                , "resource_id"
                , "resource_name"
                , "resource_width"
                , "resource_height"
                , "resource_preview_id"
                , "order"
            `, [ id, guildId, channelId, memberId, text ]);
    
        if (result.rows.length != 1) {
            throw new Error('unable to properly insert message');
        }
    
        return result.rows[0];
    }

    static async insertMessageWithResource(
        guildId: string,
        channelId: string,
        memberId: string,
        text: string | null,
        resourceId: string,
        resourceName: string,
        resourceWidth: number | null,
        resourceHeight: number | null,
        resourcePreviewId: string | null
    ): Promise<any> {
        let id = uuid.v4();
        let result = await db.query(
            `INSERT INTO "messages" (
                "id", "guild_id", "channel_id", "member_id", "text",
                "resource_id", "resource_name", "resource_width", "resource_height",
                "resource_preview_id", "sent_dtg", "order"
            ) VALUES ($1:UUID, $2, $3, $4, $5, $6, $7, $8, $9, $10, NOW(), LPAD(FLOOR(EXTRACT(epoch FROM NOW())::decimal * 100000)::text, 20, '0') || $1::text)
            RETURNING
                "id", "channel_id", "member_id"
                , "text", "sent_dtg"
                , "resource_id"
                , "resource_name"
                , "resource_width"
                , "resource_height"
                , "resource_preview_id"
                , "order"
            `, [ id, guildId, channelId, memberId, text, resourceId, resourceName, resourceWidth, resourceHeight, resourcePreviewId ]);
    
        if (result.rows.length != 1) {
            throw new Error('unable to properly insert message (with resource)');
        }

        return result.rows[0];
    }

    // Returns the resource id. Resources are deduped based on their hash
    static async insertResource(guildId: string, resourceBuff: Buffer): Promise<string> {
        // HACK: using on conflict set guild_id=guild_id to ensure that RETURNING gives the proper id and we don't need another select
        let resourceResult = await db.query(
            `INSERT INTO "resources" ("guild_id", "hash", "data") VALUES ($1, digest($2::bytea, 'sha256'), $2::bytea)
            ON CONFLICT ("guild_id", "hash") DO UPDATE
                SET "guild_id"=EXCLUDED."guild_id"
            RETURNING "id"`, [ guildId, resourceBuff ]);
        
        if (resourceResult.rows.length != 1) {
            throw new Error('unable to insert resource');
        }
        return resourceResult.rows[0].id;
    }

    // static async updateMessage(
    //     guildId: string,
    //     messageId: string,
    //     channelId: string,
    //     memberId: string,
    //     text: string | null,
    //     resourceId: string | null,
    //     resourceName: string | null,
    //     resourceWidth: number | null,
    //     resourceHeight: number | null,
    //     resourcePreviewId: string | null
    // ) {
    //     let updateResult = await db.query(
    //         `INSERT INTO "messages" (
    //             "guild_id", "channel_id", "member_id", "text",
    //             "resource_id", "resource_name", "resource_width", "resource_height",
    //             "resource_preview_id", "sent_dtg"
    //         ) VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, NOW())
    //         WHERE
    //             "guild_id"=$1
    //             AND "message_id"=$2
    //         `
    //     )
    // }

    // Resets all members status to Offline for specified guildId
    static async clearAllMemberStatus(guildId: string): Promise<void> {
        await db.query(`UPDATE "members" SET "status"='offline' WHERE "guild_id"=$1`, [ guildId ]);
    }

    // Set the status of a specified member
    static async setMemberStatus(guildId: string, memberId: string, status: string): Promise<void> {
        let result = await db.query(`
            UPDATE "members" SET "status"=$1 WHERE "guild_id"=$2 AND "id"=$3
        `, [ status, guildId, memberId ]);
        if (result.rowCount != 1) {
            throw new Error('unable to update status');
        }
    }

    // Set the display name of a specified member
    static async setMemberDisplayName(guildId: string, memberId: string, displayName: string): Promise<void> {
        let result = await db.query(`
            UPDATE "members" SET "display_name"=$1 WHERE "guild_id"=$2 AND "id"=$3
        `, [ displayName, guildId, memberId ]);
        if (result.rowCount != 1) {
            throw new Error('unable to update status');
        }
    }

    // Creates a role in the guild (returns the id)
    static async createRole(guildId: string, name: string, color: string, priority: number): Promise<string> {
        let result = await db.query(`
            INSERT INTO "roles"
                ("guild_id", "name", "color", "priority")
            VALUES
                ($1, $2, $3, $4)
            RETURNING
                "id"
        `, [ guildId, name, color, priority ]);
        if (result.rows.length != 1) {
            throw new Error('unable to create role');
        }
        return result.rows[0].id;
    }

    static async removeRole(guildId: string, roleId: string): Promise<void> {
        let result = await db.query(
            `DELETE FROM "roles" WHERE "id"=$1 AND "guild_id"=$2`,
            [ roleId, guildId ]
        );
        if (result.rowCount != 1) {
            throw new Error('unable to remove role');
        }
    }

    static async assignRoleToMember(guildId: string, roleId: string, memberId: string): Promise<void> {
        let existsResult = await db.query(`
            SELECT COUNT(*) AS c FROM "member_roles" WHERE
                "role_id" = $1
                AND "guild_id" = $2
                AND "member_id" = $3
        `, [ roleId, guildId, memberId ]);
        if (existsResult.rows.length != 1) {
            throw new Error('unable to check for existing privilege');
        }
        if (existsResult.rows[0].c != 0) {
            LOG.warn(`r#${roleId} already assigned to u#${memberId} in g#${guildId}`);
            return;
        }
        let result = await db.query(`
            INSERT INTO "member_roles"
                ("role_id", "guild_id", "member_id")
            VALUES
                ($1, $2, $3)
            RETURNING
                "role_id"
        `, [ roleId, guildId, memberId ]);
        if (result.rows.length != 1) {
            throw new Error('unable to assign user to role');
        }
    }

    static async revokeRoleFromMember(guildId: string, roleId: string, memberId: string): Promise<void> {
        let existsResult = await db.query(`
            SELECT COUNT(*) AS c FROM "member_roles" WHERE
                "role_id" = $1
                AND "guild_id" = $2
                AND "member_id" = $3
        `, [ roleId, guildId, memberId ]);
        if (existsResult.rows.length != 1) {
            throw new Error('unable to check for existing privilege');
        }
        if (existsResult.rows[0].c == 0) {
            LOG.warn(`r#${roleId} was never assigned to u#${memberId} in g#${guildId}`);
            return;
        }
        let result = await db.query(`
            DELETE FROM "member_roles"
            WHERE
                "role_id"=$1
                AND "guild_id"=$2
                AND "member_id"=$3
        `, [ roleId, guildId, memberId ]);
        if (result.rowCount != 1) {
            throw new Error('unable to revoke role from user');
        }
    }

    static async assignRolePrivilege(guildId: string, roleId: string, privilege: string): Promise<void> {
        let existsResult = await db.query(`
            SELECT COUNT(*) AS c FROM "role_privileges" WHERE
                "role_id" = $1
                AND "guild_id" = $2
                AND "privilege" = $3
        `, [ roleId, guildId, privilege ]);
        if (existsResult.rows.length != 1) {
            throw new Error('unable to check for existing privilege');
        }
        if (existsResult.rows[0].c != 0) {
            LOG.warn(`privilege ${privilege} already exists for r#${roleId} on g#${guildId}`);
            return;
        }
        let result = await db.query(`
            INSERT INTO "role_privileges"
                ("role_id", "guild_id", "privilege")
            VALUES
                ($1, $2, $3)
            RETURNING
                "role_id"
        `, [ roleId, guildId, privilege ]);
        if (result.rows.length != 1) {
            throw new Error('unable to add privilege to role privileges');
        }
    }

    static async revokeRolePrivilege(roleId: string, guildId: string, privilege: string): Promise<void> {
        let existsResult = await db.query(`
            SELECT COUNT(*) AS c FROM "role_privileges" WHERE
                "role_id" = $1
                AND "guild_id" = $2
                AND "privilege" = $3
        `, [ roleId, guildId, privilege ]);
        if (existsResult.rows.length != 1) {
            throw new Error('unable to check for existing privilege');
        }
        if (existsResult.rows[0].c == 0) {
            LOG.warn(`privilege ${privilege} did not exist for r#${roleId} on g#${guildId}`);
            return;
        }
        let result = await db.query(`
            DELETE FROM "role_privileges"
            WHERE
                "role_id"=$1
                , "guild_id"=$2
                , "privilege"=$3
        `, [ roleId, guildId, privilege ]);
        if (result.rowCount != 1) {
            throw new Error('unable to revoke privilege to role privileges');
        }
    }

    static async hasPrivilege(guildId: string, memberId: string, privilege: string): Promise<boolean> {
        let result = await db.query(`
            SELECT COUNT(*) AS c FROM
                member_roles
                , role_privileges
            WHERE
                member_roles.role_id=role_privileges.role_id
                AND member_roles.guild_id=$1
                AND member_roles.member_id=$2
                AND role_privileges.privilege=$3
        `, [ guildId, memberId, privilege ]);
        if (result.rows.length != 1) {
            throw new Error('unable to check for privilege');
        }
        return result.rows[0].c > 0;
    }

    static async setMemberAvatarResourceId(guildId: string, memberId: string, avatarResourceId: string): Promise<void> {
        let result = await db.query(`
            UPDATE "members" SET "avatar_resource_id"=$1 WHERE "guild_id"=$2 AND "id"=$3
        `, [ avatarResourceId, guildId, memberId ]);
        if (result.rowCount != 1) {
            throw new Error('unable to update status');
        }
    }

    static async getTokens(guildId: string): Promise<any[]> {
        let result = await db.query(`
            SELECT "token", "member_id", "created", "expires" FROM tokens
            WHERE "guild_id"=$1
        `, [ guildId]);
        return result.rows;
    }

    //insert into tokens (guild_id, expires) VALUES ('226b3e9e-5220-4205-bf5b-6738b9b3bb39', NOW() + '7 days'::interval) RETURNING "token", "expires";
    static async createToken(guildId: string, expiresAfter: string): Promise<any> {
        let result = await db.query(`
            INSERT INTO "tokens" ("guild_id", "expires")
            VALUES ($1, NOW() + $2::interval)
            RETURNING "token", "expires"
        `, [ guildId, expiresAfter ]);
        if (result.rows.length != 1) {
            throw new Error('unable to insert a token');
        }
        return result.rows[0];
    }

    static async isTokenReal(token: string): Promise<boolean> {
        let result = await db.query(`SELECT COUNT(*) AS c FROM "tokens" WHERE "token"=$1`, [ token ]);
        return result.rows[0].c == 1;
    }

    static async isTokenForGuild(token: string, guildId: string): Promise<boolean> {
        let result = await db.query(`SELECT COUNT(*) AS c FROM "tokens" WHERE "token"=$1 AND "guild_id"=$2`, [ token, guildId ]);
        return result.rows[0].c == 1;
    }

    static async isTokenTaken(token: string): Promise<boolean> {
        let result = await db.query(`SELECT COUNT(*) AS c FROM "tokens" WHERE "token"=$1 AND "member_id" IS NOT NULL`, [ token ]);
        return result.rows[0].c == 1;
    }

    static async isTokenActive(token: string): Promise<boolean> {
        let result = await db.query(`SELECT COUNT(*) AS c FROM "tokens" WHERE "token"=$1 AND "member_id" IS NULL AND "expires">NOW()`, [ token ]);
        return result.rows[0].c == 1;
    }

    // registers a user for with a token
    // NOTE: Tokens are unique across guilds so they can be used to get the guildId
    static async registerWithToken(token: string, derBuff: Buffer, displayName: string, avatarBuff: Buffer): Promise<{ guildId: string, memberId: string }> {
        // insert avatar as resource
        let result: { memberId: string, guildId: string } | null = null;
        await DB.queueTransaction(async () => {
            let resultguildId = await db.query(`
                SELECT "guild_id" FROM "tokens" WHERE "token"=$1
            `, [ token ]);
            if (resultguildId.rows.length != 1) {
                throw new Error('unable to get token guild id');
            }
            let guildId = resultguildId.rows[0].guild_id as string;
            let avatarResourceId = await DB.insertResource(guildId, avatarBuff);
            let resultInsertMember = await db.query(`
                INSERT INTO "members" (
                    "guild_id", "public_key", "display_name", "avatar_resource_id"
                ) VALUES ($1, $2, $3, $4)
                RETURNING "id"
            `, [ guildId, derBuff, displayName, avatarResourceId ]);
            if (resultInsertMember.rows.length != 1) {
                throw new Error('unable to insert member');
            }
            let memberId = resultInsertMember.rows[0].id;
            let resultUpdate = await db.query(`
                UPDATE "tokens" SET "member_id"=$1 WHERE "token"=$2
            `, [ memberId, token ]);
            if (resultUpdate.rowCount != 1) {
                throw new Error('unable to update token with new member');
            }
            result = { guildId, memberId };
        });
        if (!result) {
            throw new Error('result was not set');
        }
        return result;
    }

    static async revokeToken(token: string): Promise<void> {
        let result = await db.query('DELETE FROM "tokens" WHERE "token"=$1', [ token ]);
        if (result.rowCount != 1) {
            throw new Error('unable to remove token');
        }
    }
}