using Insight.Database;
using System.Data;

namespace Database.ConfigurationManagementSystem;

public class ConfigurationDatabaseSetup
{
    private readonly IDbConnection _connection;

    public ConfigurationDatabaseSetup(IDbConnection connection)
    {
        _connection = connection;
    }
    public async Task CreateDatabaseStructure(IDbConnection connection)
    {
        await CreateConfigurationTable();
        await CreateHistoryTable();
        await CreateConfigurationIndexes();
        await CreateModifiedAtTrigger();
        await CreateNotifyTrigger();
        await CreateHistoryTrigger();
    }

    public async Task CreateConfigurationTable()
    {
        const string sql = @"
                            CREATE TABLE app_configuration (
                                id bigserial NOT NULL,
                                ""key"" varchar(255) NOT NULL,
                                value text NULL,
                                ""label"" varchar(255) NULL,
                                content_type varchar(255) DEFAULT 'text/plain'::character varying NULL,
                                valid_from timestamptz NULL,
                                expires_at timestamptz NULL,
                                created_at timestamptz DEFAULT CURRENT_TIMESTAMP NULL,
                                modified_at timestamptz DEFAULT CURRENT_TIMESTAMP NULL,
                                etag uuid DEFAULT gen_random_uuid() NULL,
                                CONSTRAINT app_configuration_pkey PRIMARY KEY (id)
                            );";
        await _connection.ExecuteAsync(sql);
    }

    public async Task CreateHistoryTable()
    {
        const string sql = @"
                            CREATE TABLE app_configuration_history (
                                history_id bigserial NOT NULL,
                                action_type char(1) NOT NULL,
                                action_timestamp timestamptz NOT NULL DEFAULT CURRENT_TIMESTAMP,
                                action_by text NOT NULL DEFAULT CURRENT_USER,
                                id bigint NOT NULL,
                                ""key"" varchar(255) NOT NULL,
                                value text NULL,
                                ""label"" varchar(255) NULL,
                                content_type varchar(255) NULL,
                                valid_from timestamptz NULL,
                                expires_at timestamptz NULL,
                                created_at timestamptz NULL,
                                modified_at timestamptz NULL,
                                etag uuid NULL,
                                CONSTRAINT app_configuration_history_pkey PRIMARY KEY (history_id)
                            );";
        await _connection.ExecuteAsync(sql);
    }

    public async Task CreateConfigurationIndexes()
    {
        const string sql = @"
                            CREATE INDEX idx_app_configuration_key ON app_configuration(""key"");
                            CREATE INDEX idx_app_configuration_validity ON app_configuration(valid_from, expires_at);";
        await _connection.ExecuteAsync(sql);
    }

    public async Task CreateModifiedAtTrigger()
    {
        const string sql = @"
                            CREATE OR REPLACE FUNCTION update_app_configuration_modified_at()
                            RETURNS TRIGGER AS $$
                            BEGIN
                                NEW.modified_at = CURRENT_TIMESTAMP;
                                RETURN NEW;
                            END;
                            $$ LANGUAGE plpgsql;

                            CREATE TRIGGER trg_app_configuration_modified_at
                                BEFORE UPDATE ON app_configuration
                                FOR EACH ROW
                                EXECUTE FUNCTION update_app_configuration_modified_at();";
        await _connection.ExecuteAsync(sql);
    }

    public async Task CreateNotifyTrigger()
    {
        const string sql = @"
                            CREATE OR REPLACE FUNCTION notify_app_configuration_change()
                            RETURNS TRIGGER AS $$
                            BEGIN
                                PERFORM pg_notify('config_changes', NEW.key);
                                RETURN NEW;
                            END;
                            $$ LANGUAGE plpgsql;

                            CREATE TRIGGER trg_app_configuration_notify
                                AFTER INSERT OR UPDATE ON app_configuration
                                FOR EACH ROW
                                EXECUTE FUNCTION notify_app_configuration_change();";
        await _connection.ExecuteAsync(sql);
    }

    public async Task CreateHistoryTrigger()
    {
        const string sql = @"
                            CREATE OR REPLACE FUNCTION log_app_configuration_changes()
                            RETURNS TRIGGER AS $$
                            BEGIN
                                IF (TG_OP = 'INSERT') THEN
                                    INSERT INTO app_configuration_history (
                                        action_type, id, ""key"", value, label, content_type, 
                                        valid_from, expires_at, created_at, modified_at, etag
                                    )
                                    VALUES (
                                        'I', NEW.id, NEW.key, NEW.value, NEW.label, NEW.content_type,
                                        NEW.valid_from, NEW.expires_at, NEW.created_at, NEW.modified_at, NEW.etag
                                    );
                                ELSIF (TG_OP = 'UPDATE') THEN
                                    INSERT INTO app_configuration_history (
                                        action_type, id, ""key"", value, label, content_type,
                                        valid_from, expires_at, created_at, modified_at, etag
                                    )
                                    VALUES (
                                        'U', OLD.id, OLD.key, OLD.value, OLD.label, OLD.content_type,
                                        OLD.valid_from, OLD.expires_at, OLD.created_at, OLD.modified_at, OLD.etag
                                    );
                                ELSIF (TG_OP = 'DELETE') THEN
                                    INSERT INTO app_configuration_history (
                                        action_type, id, ""key"", value, label, content_type,
                                        valid_from, expires_at, created_at, modified_at, etag
                                    )
                                    VALUES (
                                        'D', OLD.id, OLD.key, OLD.value, OLD.label, OLD.content_type,
                                        OLD.valid_from, OLD.expires_at, OLD.created_at, OLD.modified_at, OLD.etag
                                    );
                                END IF;
                                RETURN NULL;
                            END;
                            $$ LANGUAGE plpgsql;

                            CREATE TRIGGER trg_app_configuration_history
                                AFTER INSERT OR UPDATE OR DELETE ON app_configuration
                                FOR EACH ROW EXECUTE FUNCTION log_app_configuration_changes();";
        await _connection.ExecuteAsync(sql);
    }


}