use std::collections::{BTreeMap, BTreeSet};
use std::fmt;
use std::mem::take;

use error_chain::bail;
use log::{debug, error, trace};
use serde_derive::{Deserialize, Serialize};
use url::Url;

use crate::errors::*;
use crate::model::connection::Connection;
use crate::model::connection::Direction;
use crate::model::connection::Direction::FROM;
use crate::model::connection::Direction::TO;
use crate::model::input::InputInitializer;
use crate::model::io::{IO, IOType};
use crate::model::io::Find;
use crate::model::io::IOSet;
use crate::model::metadata::MetaData;
use crate::model::name::HasName;
use crate::model::name::Name;
use crate::model::process::Process;
use crate::model::process::Process::FlowProcess;
use crate::model::process::Process::FunctionProcess;
use crate::model::process_reference::ProcessReference;
use crate::model::route::{Route, RouteType};
use crate::model::route::HasRoute;
use crate::model::route::SetIORoutes;
use crate::model::route::SetRoute;
use crate::model::validation::Validate;

/// `FlowDefinition` defines (at compile time) a parent or child flow in the nested flow hierarchy
#[derive(Serialize, Deserialize, Debug, Clone)]
#[serde(deny_unknown_fields)]
pub struct FlowDefinition {
    /// `name` given to this flow
    #[serde(rename = "flow")]
    pub name: Name,
    /// `inputs` that this flow defines
    #[serde(default, rename = "input")]
    pub inputs: IOSet,
    /// `outputs` that this flow defines
    #[serde(default, rename = "output")]
    pub outputs: IOSet,
    /// Set of sub-processes referenced (used) in this flow
    #[serde(default, rename = "process")]
    pub process_refs: Vec<ProcessReference>,
    /// `connections` within this flow, from flow input or to flow outputs
    #[serde(default, rename = "connection")]
    pub connections: Vec<Connection>,
    /// `metadata` about flow author, versions etc
    #[serde(default)]
    pub metadata: MetaData,
    /// Name of any docs file associated with this Flow
    #[serde(default)]
    pub docs: String,

    /// When the same process is used multiple times within a single flow, to disambiguate
    /// between them each one must be given an alias that is used to refer to it
    #[serde(skip)]
    pub alias: Name,
    /// flows are assigned a numeric `id` in the hierarchy
    #[serde(skip)]
    pub id: usize,
    /// `source_url` is the url of the file/resource where this flow definition was read from
    #[serde(skip, default = "FlowDefinition::default_url")]
    pub source_url: Url,
    /// `route` defines the location in the hierarchy of flows where this ones resides
    #[serde(skip)]
    pub route: Route,
    /// `subprocesses` are the loaded definition of the processes reference (used) within this flow
    #[serde(skip)]
    pub subprocesses: BTreeMap<Name, Process>,
    /// `lib_references` is the set of library references used in this flow
    #[serde(skip)]
    pub lib_references: BTreeSet<Url>,
    /// `context_references` is the set of context functions used in this flow
    #[serde(skip)]
    pub context_references: BTreeSet<Url>,
}

impl Validate for FlowDefinition {
    // check the correctness of all the fields in this flow, prior to loading sub-elements
    fn validate(&self) -> Result<()> {
        for input in &self.inputs {
            input.validate()?;
        }

        for output in &self.outputs {
            output.validate()?;
        }

        for connection in &self.connections {
            connection.validate()?;
        }

        Ok(())
    }
}

impl fmt::Display for FlowDefinition {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        writeln!(f, "\tname: \t\t\t{}\n\tid: \t\t\t{}\n\talias: \t\t\t{}\n\tsource_url: \t{}\n\troute: \t\t\t{}",
                 self.name, self.id, self.alias, self.source_url, self.route)?;

        writeln!(f, "\tinputs:")?;
        for input in &self.inputs {
            writeln!(f, "\t\t\t\t\t{input:#?}")?;
        }

        writeln!(f, "\toutputs:")?;
        for output in &self.outputs {
            writeln!(f, "\t\t\t\t\t{output:#?}")?;
        }

        writeln!(f, "\tprocesses:")?;
        for flow_ref in &self.process_refs {
            writeln!(f, "\t{flow_ref}")?;
        }

        writeln!(f, "\tconnections:")?;
        for connection in &self.connections {
            writeln!(f, "\t\t\t\t\t{connection}")?;
        }

        Ok(())
    }
}

impl Default for FlowDefinition {
    fn default() -> FlowDefinition {
        FlowDefinition {
            name: Default::default(),
            inputs: vec![],
            outputs: vec![],
            process_refs: vec![],
            connections: vec![],
            metadata: Default::default(),
            docs: "".to_string(),
            alias: Default::default(),
            id: 0,
            source_url: Url::parse("file://").expect("Could not create Url"),
            route: Default::default(),
            subprocesses: Default::default(),
            lib_references: Default::default(),
            context_references: Default::default(),
        }
    }
}

impl HasName for FlowDefinition {
    fn name(&self) -> &Name {
        &self.name
    }

    fn alias(&self) -> &Name {
        &self.alias
    }
}

impl HasRoute for FlowDefinition {
    fn route(&self) -> &Route {
        &self.route
    }
    fn route_mut(&mut self) -> &mut Route {
        &mut self.route
    }
}

impl SetRoute for FlowDefinition {
    fn set_routes_from_parent(&mut self, parent_route: &Route) {
        if parent_route.is_empty() {
            self.route = Route::from(format!("/{}", self.alias));
        } else {
            self.route = Route::from(format!("{parent_route}/{}", self.alias));
        }
        self.inputs
            .set_io_routes_from_parent(&self.route, IOType::FlowInput);
        self.outputs
            .set_io_routes_from_parent(&self.route, IOType::FlowOutput);
    }
}

impl FlowDefinition {
    /// Return a default value for a Url as part of a flow
    pub fn default_url() -> Url {
        Url::parse("file://").expect("Could not create default_url")
    }

    /// Set the alias of this flow to the supplied Name
    pub fn set_alias(&mut self, alias: &Name) {
        if alias.is_empty() {
            self.alias = self.name.clone();
        } else {
            self.alias = alias.clone();
        }
    }

    /// Get the name of any associated docs file
    pub fn get_docs(&self) -> &str {
        &self.docs
    }

    /// Get a reference to the set of inputs this flow defines
    pub fn inputs(&self) -> &IOSet {
        &self.inputs
    }

    /// Get a mutable reference to the set of inputs this flow defines
    pub fn inputs_mut(&mut self) -> &mut IOSet {
        &mut self.inputs
    }

    /// Get a reference to the set of outputs this flow defines
    pub fn outputs(&self) -> &IOSet {
        &self.outputs
    }

    /// Set the origin id of all connections to be this flow
    pub fn set_connection_origin_flow_ids(&mut self) {
        for connection in &mut self.connections {
            connection.set_origin_flow_id(self.id);
        }
    }

    /// Set the initial values on the IOs in an IOSet using a set of Input Initializers
    fn set_initializers(&mut self, initializer_map: &BTreeMap<String, InputInitializer>)
    -> Result<()> {
        for (input_name, initializer) in initializer_map {
            // Go through all inputs matching names with names used in initializers
            for (index, input) in self.inputs.iter_mut().enumerate() {
                if *input.name() == Name::from(input_name)
                    || (input_name.as_str() == "default" && index == 0)
                {
                    input.set_initializer(Some(initializer.clone()))
                        .chain_err(|| "Failed to set initializers in flow")?;
                }
            }
        }
        Ok(())
    }

    /// Configure a flow with additional information after it is deserialized from file
    pub fn config(
        &mut self,
        source_url: &Url,
        parent_route: &Route,
        alias_from_reference: &Name,
        id: usize,
        initializations: &BTreeMap<String, InputInitializer>,
    ) -> Result<()> {
        self.id = id;
        self.set_alias(alias_from_reference);
        self.source_url = source_url.to_owned();
        self.set_initializers(initializations)?;
        self.set_connection_origin_flow_ids();
        self.set_routes_from_parent(parent_route);
        self.validate()
    }

    /// Check if the flow can be run (it could be a sub-flow not a context level runnable flow)
    pub fn is_runnable(&self) -> bool {
        self.inputs().is_empty() && self.outputs().is_empty()
    }

    fn get_subprocess_io(
        &mut self,
        subprocess_alias: &Name,
        direction: Direction,
        sub_route: &Route,
    ) -> Result<IO> {
        debug!("\tLooking for subprocess with alias = '{}'", subprocess_alias);

        // TODO create a trait HasInputs and HasOutputs and implement it for function and flow
        // and process so this below can avoid the match
        match self.subprocesses.get_mut(subprocess_alias) {
            Some(FlowProcess(ref mut sub_flow)) => {
                debug!(
                    "\tFlow sub-process with matching name found, name = '{}'",
                    subprocess_alias
                );
                match direction {
                    TO => sub_flow
                        .inputs
                        .find_by_subroute(sub_route),
                    FROM => sub_flow
                        .outputs
                        .find_by_subroute(sub_route),
                }
            },

            Some(FunctionProcess(ref mut function)) => {
                debug!(
                    "\tFunction sub-process with name = '{}' found",
                    subprocess_alias
                );
                match direction {
                    TO => function.inputs.find_by_subroute(sub_route),
                    FROM => function.outputs.find_by_subroute(sub_route)
                        .or_else(|e1| { // for connections FROM the Input value copied at the output
                            function.inputs.find_by_subroute(sub_route)
                                .chain_err(|| e1 )
                        }),
                }
            }

            None => {
                    bail!("No sub-process named '{subprocess_alias}' exists in the flow '{}'\n\
                possible sub-process names are: '{}'",
                        self.route, self.subprocesses.keys().map(|k| k.as_str() )
                            .collect::<Vec<&str>>().join(", "))
            }
        }
    }

    fn parse_subroute(&self, route: &Route) -> Result<RouteType> {
        let segments: Vec<&str> = route.split('/').collect();

        match segments[0] {
            "input" => Ok(RouteType::FlowInput(segments[1].into(),
                                        segments[2..].join("/").into())),
            "output" => Ok(RouteType::FlowOutput(segments[1].into())),
            "" => bail!("Invalid Route in connection - must be an input, output or sub-process name"),
            process_name => Ok(RouteType::SubProcess(process_name.into(),
                                         segments[1..].join("/").into())),
        }
    }

    // Find an IO in a flow using its Route. Depending on the direction, possible IOs inside a flow are:
    //
    // FROM an Input of the Flow itself (FlowInput)
    // TO an Output of the Flow itself (FlowOutput)
    //
    // TO or FROM an Input/Output of a subprocess (subflow, or function) (SubProcess)
    //
    // Invalid Connections are:
    // FROM a FLowOutput
    // TO a FlowInput
    fn get_io_by_route(
        &mut self,
        direction: Direction,
        route: &Route,
    ) -> Result<IO> {
        debug!("Looking for connection {:?} '{}'", direction, route);
        match (&direction, self.parse_subroute(route)?) {
            (&FROM, RouteType::FlowInput(input_name, sub_route)) => {
                // make sure the sub-route of the input is added to the source of the connection
                let mut from = self
                    .inputs
                    .find_by_subroute(&Route::from(input_name.to_string()))?;
                // accumulate any subroute within the input
                from.route_mut().extend(&sub_route);
                Ok(from)
            },

            (&TO, RouteType::FlowOutput(output_name)) =>
                self.outputs.find_by_subroute(&Route::from(output_name.to_string())),

            (_, RouteType::SubProcess(process_name, sub_route)) =>
                self.get_subprocess_io(&process_name, direction, &sub_route),

            (&FROM, RouteType::FlowOutput(output_name)) => {
                bail!("Invalid connection FROM an output named: '{}'", output_name)
            },

            (&TO, RouteType::FlowInput(input_name, sub_route)) => {
                bail!(
                    "Invalid connection TO an input named: '{}' with sub_route: '{}'",
                    input_name, sub_route
                )
            }
        }
    }

    /// Iterate over all the connections defined in the flow, and attempt to connect the source
    /// and destination (within the flow), checking the two types are compatible
    pub fn build_connections(&mut self, level: usize) -> Result<()> {
        debug!("Building connections for flow '{}'", self.name);

        let mut error_count = 0;

        // get connections out of self - so we can use immutable references to self inside loop
        let mut connections = take(&mut self.connections);

        for connection in connections.iter_mut() {
            if let Err(e) = self.build_connection(connection, level) {
                error_count += 1;
                error!("{}", e);
            }
        }

        if error_count == 0 {
            debug!(
                "All connections inside flow '{}' successfully built",
                self.source_url
            );
            Ok(())
        } else {
            bail!(
                "{} connection errors found in flow '{}'",
                error_count,
                self.source_url
            )
        }
    }

    // Connection to/from Formats:
    // "input/input_name"       - An Input of this Flow
    // "output/output_name"     - An Output of this Flow
    // "flow_name/io_name"      - An Input or Output of a sub-flow within this flow
    // "function_name/io_name"  - An Input or an Output of a function within this flow
    //
    // Propagate any initializers on a flow output to the input (subflow or function) it is connected to
    fn build_connection(&mut self, connection: &mut Connection, level: usize) -> Result<()> {
        let from_io = self.get_io_by_route(FROM, connection.from())
            .chain_err(|| format!("Did not find connection source: '{}' specified in flow '{}'\n",
                   connection.from(), self.source_url))?;
        trace!("Found connection source:\n{:#?}", from_io);

        // Connection can specify multiple destinations within flow - iterate over them all
        for to_route in connection.to() {
            match self.get_io_by_route(TO, to_route) {
                Ok(to_io) => {
                    trace!("Found connection destination:\n{:#?}", to_io);
                    let mut new_connection = connection.clone();
                    new_connection.connect(from_io.clone(), to_io, level)?;
                    self.connections.push(new_connection);
                }
                Err(error) => {
                    bail!(
                        "Did not find connection destination: '{}' in flow '{}'\n\t\t{}",
                        to_route,
                        self.source_url,
                        error
                    );
                }
            }
        }
        Ok(())
    }
}

#[cfg(test)]
mod test {
    use std::collections::BTreeMap;

    use serde_json::json;

    use crate::model::connection::{Connection, Direction};
    use crate::model::datatype::{NUMBER_TYPE, STRING_TYPE};
    use crate::model::flow_definition::FlowDefinition;
    use crate::model::function_definition::FunctionDefinition;
    use crate::model::input::InputInitializer::Always;
    use crate::model::input::InputInitializer::Once;
    use crate::model::io::IO;
    use crate::model::name::{HasName, Name};
    use crate::model::process::Process;
    use crate::model::route::{HasRoute, Route, SetRoute, RouteType};
    use crate::model::validation::Validate;

    // Create a test flow we can use in connection building testing
    fn test_flow() -> FlowDefinition {
        let mut flow = FlowDefinition {
            name: "test_flow".into(),
            alias: "test_flow".into(),
            inputs: vec![
                IO::new_named(vec!(STRING_TYPE.into()), "string", "string"),
                IO::new_named(vec!(NUMBER_TYPE.into()), "number", "number"),
            ],
            outputs: vec![
                IO::new_named(vec!(STRING_TYPE.into()), "string", "string"),
                IO::new_named(vec!(NUMBER_TYPE.into()), "number", "number"),
            ],
            source_url: FlowDefinition::default_url(),
            ..Default::default()
        };

        let process_1 = Process::FunctionProcess(FunctionDefinition {
            name: "process_1".into(),
            inputs: vec![IO::new_named(vec!(STRING_TYPE.into()),
                                       "", "")],
            outputs: vec![IO::new_named(vec!(STRING_TYPE.into()),
                                        "output_1", "output_1")],
            ..Default::default()
        });

        let process_2 = Process::FunctionProcess(FunctionDefinition {
            name: "process_2".into(),
            function_id: 1,
            inputs: vec![IO::new_named(vec!(STRING_TYPE.into()), "", "")],
            outputs: vec![IO::new_named(vec!(NUMBER_TYPE.into()), "", "")],
            ..Default::default()
        });

        let _ = flow.subprocesses.insert("process_1".into(), process_1);
        let _ = flow.subprocesses.insert("process_2".into(), process_2);

        flow
    }

    #[test]
    fn test_name() {
        let flow = FlowDefinition::default();
        assert_eq!(flow.name(), &Name::default());
    }

    #[test]
    fn test_alias() {
        let flow = FlowDefinition::default();
        assert_eq!(flow.alias(), &Name::default());
    }

    #[test]
    fn test_set_alias() {
        let mut flow = FlowDefinition::default();
        flow.set_alias(&Name::from("test flow"));
        assert_eq!(flow.alias(), &Name::from("test flow"));
    }

    #[test]
    fn test_set_empty_alias() {
        let mut flow = FlowDefinition::default();
        flow.set_alias(&Name::from(""));
        assert_eq!(flow.alias(), &Name::from(""));
    }

    #[test]
    fn test_route() {
        let flow = FlowDefinition::default();
        assert_eq!(flow.route(), &Route::default());
    }

    #[test]
    fn test_invalid_connection_route() {
        let flow = test_flow();
        match flow.parse_subroute(&Route::from("")) {
            Ok(_) => panic!("Connection route should not be valid"),
            Err(e) => assert!(e.to_string()
                    .contains("Invalid Route in connection"))
        }
    }

    #[test]
    fn test_parse_valid_input() {
        let flow = test_flow();
        assert_eq!(flow.parse_subroute(&Route::from("input/string"))
                       .expect("Could not find input"),
                   RouteType::FlowInput(Name::from("string"),
                                           Route::default()));
    }

    #[test]
    fn test_parse_valid_output() {
        let flow = test_flow();
        assert_eq!(flow.parse_subroute(&Route::from("output/string"))
                       .expect("Could not find input"),
                   RouteType::FlowOutput(Name::from("string")));
    }

    #[test]
    fn test_parse_valid_subprocess() {
        let flow = test_flow();
        assert_eq!(flow.parse_subroute(&Route::from("sub-process"))
                       .expect("Could not find input"),
                   RouteType::SubProcess(Name::from("sub-process"), Route::default()));
    }

    #[test]
    fn test_non_existent_subprocess_in_connection() {
        let mut flow = test_flow();
        match flow.get_subprocess_io(&Name::from("blablabla"),
                                     Direction::FROM,
                                     &Route::from("who-cares")) {
            Ok(_) => panic!("Should not find non-existent sub-process"),
            Err(e) => {
                assert!(e.to_string().contains("No sub-process named"))
            },
        }
    }

    #[test]
    fn test_existent_subprocess_existing_io_in_connection() {
        let mut flow = test_flow();
        flow.get_subprocess_io(&Name::from("process_1"),
                                     Direction::FROM,
                                     &Route::from(""))
            .expect("Could not find sub-process called process_1");
    }

    #[test]
    fn test_existent_subprocess_non_existing_input_in_connection() {
        let mut flow = test_flow();
        match flow.get_subprocess_io(&Name::from("process_1"),
                                     Direction::TO,
                                     &Route::from("no-such-io")) {

            Ok(_) => panic!("Should not find non-existent sub-process input"),
            Err(e) => assert!(e.to_string().contains("No IO"))
        }
    }

    #[test]
    fn test_existent_subprocess_non_existing_io_in_connection() {
        let mut flow = test_flow();
        match flow.get_subprocess_io(&Name::from("process_1"),
                               Direction::FROM,
                               &Route::from("no-such-io")) {

            Ok(_) => panic!("Should not find non-existent sub-process IO"),
            Err(e) => {
                assert!(e.to_string().contains("No IO"))
            },
        }
    }

    #[test]
    fn test_route_mut() {
        let mut flow = FlowDefinition::default();
        let route = flow.route_mut();
        assert_eq!(route, &Route::default());
        *route = Route::from("/root");
        assert_eq!(route, &Route::from("/root"));
    }

    #[test]
    fn test_set_empty_parent_route() {
        let mut flow = test_flow();
        flow.set_routes_from_parent(&Route::from(""));
        assert_eq!(flow.route(), &Route::from("/test_flow"));
    }

    #[test]
    fn test_set_parent_route() {
        let mut flow = test_flow();
        flow.set_routes_from_parent(&Route::from("/root"));
        assert_eq!(flow.route(), &Route::from("/root/test_flow"));
    }

    #[test]
    fn validate_flow() {
        let mut flow = test_flow();
        let connection = Connection::new("process_1", "process_2");
        flow.connections = vec![connection];
        assert!(flow.validate().is_ok());
    }

    #[test]
    fn duplicate_connection() {
        let mut flow = test_flow();
        let connection = Connection::new("process_1", "process_2");
        flow.connections = vec![connection.clone(), connection];
        assert!(flow.validate().is_ok());
    }

    #[test]
    fn check_outputs() {
        let flow = test_flow();
        assert_eq!(flow.outputs().len(), 2);
    }

    #[test]
    fn check_inputs() {
        let flow = test_flow();
        assert_eq!(flow.inputs().len(), 2);
    }

    #[test]
    fn check_inputs_mut() {
        let mut flow = test_flow();
        let inputs = flow.inputs_mut();
        assert_eq!(inputs.len(), 2);
        *inputs = vec![];
        assert_eq!(inputs.len(), 0);
    }

    #[test]
    fn test_inputs_initializers() {
        let mut flow = test_flow();
        let mut initializers = BTreeMap::new();
        initializers.insert(STRING_TYPE.into(), Always(json!("Hello")));
        initializers.insert(NUMBER_TYPE.into(), Once(json!(42)));
        flow.set_initializers(&initializers).expect("Could not set initializers");

        assert_eq!(
            flow.inputs()
                .get(0)
                .expect("Could not get input")
                .get_initializer()
                .as_ref()
                .expect("Could not get initializer"),
            &Always(json!("Hello"))
        );

        assert_eq!(
            flow.inputs()
                .get(1)
                .expect("Could not get input")
                .get_initializer()
                .as_ref()
                .expect("Could not get initializer"),
            &Once(json!(42))
        );
    }

    #[test]
    fn display_flow() {
        let mut flow = test_flow();
        let connection = Connection::new("process_1", "process_2");
        flow.connections = vec![connection];
        println!("flow: {flow}");
    }

    mod build_connection_tests {
        use crate::model::connection::Connection;
        use crate::model::flow_definition::test::test_flow;

        #[test]
        fn build_compatible_internal_connection() {
            let mut flow = test_flow();
            let mut connection = Connection::new("process_1", "process_2");
            assert!(flow.build_connection(&mut connection, 0).is_ok());
        }

        #[test]
        fn build_incompatible_internal_connection() {
            let mut flow = test_flow();
            let mut connection = Connection::new("process_2", "process_1");
            assert!(flow.build_connection(&mut connection, 0).is_err());
        }

        #[test]
        fn build_from_flow_input_to_sub_process() {
            let mut flow = test_flow();
            let mut connection = Connection::new("input/string", "process_1");
            assert!(flow.build_connection(&mut connection, 1).is_ok());
        }

        #[test]
        fn build_from_sub_process_flow_output() {
            let mut flow = test_flow();
            let mut connection = Connection::new("process_1", "output/string");
            assert!(flow.build_connection(&mut connection, 0).is_ok());
        }

        #[test]
        fn build_from_flow_input_to_flow_output() {
            let mut flow = test_flow();
            let mut connection = Connection::new("input/string", "output/string");
            assert!(flow.build_connection(&mut connection, 1).is_ok());
        }

        #[test]
        fn build_incompatible_from_flow_input_to_sub_process() {
            let mut flow = test_flow();
            let mut connection = Connection::new("input/number", "process_1");
            assert!(flow.build_connection(&mut connection, 1).is_err());
        }

        #[test]
        fn build_incompatible_from_sub_process_flow_output() {
            let mut flow = test_flow();
            let mut connection = Connection::new("process_1", "output/number");
            assert!(flow.build_connection(&mut connection, 0).is_err());
        }

        #[test]
        fn build_incompatible_from_flow_input_to_flow_output() {
            let mut flow = test_flow();
            let mut connection = Connection::new("input/string", "output/number");
            assert!(flow.build_connection(&mut connection, 1).is_err());
        }

        #[test]
        fn fail_build_from_flow_input_to_flow_input() {
            let mut flow = test_flow();
            let mut connection = Connection::new("input/string", "input/number");
            assert!(flow.build_connection(&mut connection, 1).is_err());
        }

        #[test]
        fn fail_build_from_flow_output_to_flow_output() {
            let mut flow = test_flow();
            let mut connection = Connection::new("output/string", "output/number");
            assert!(flow.build_connection(&mut connection, 1).is_err());
        }

        #[test]
        fn build_all_flow_connections() {
            let mut flow = test_flow();

            let connection1 = Connection::new("input/string", "output/string");
            let connection2 = Connection::new("input/string", "process_1");
            let connection3 = Connection::new("process_1", "output/string");

            flow.connections = vec![connection1, connection2, connection3];
            assert!(flow.build_connections(0).is_ok());
        }

        #[test]
        fn fail_build_flow_connections() {
            let mut flow = test_flow();
            let connection1 = Connection::new("input/number", "process_1");
            flow.connections = vec![connection1];
            assert!(flow.build_connections(0).is_err());
        }
    }
}