use crate::commands::WholeStreamCommand;
use crate::prelude::*;
use indexmap::map::IndexMap;
use log::trace;
use nu_errors::ShellError;
use nu_protocol::{Primitive, ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
use nu_source::Tagged;

pub struct Which;

#[async_trait]
impl WholeStreamCommand for Which {
    fn name(&self) -> &str {
        "which"
    }

    fn signature(&self) -> Signature {
        Signature::build("which")
            .required("application", SyntaxShape::String, "application")
            .switch("all", "list all executables", Some('a'))
    }

    fn usage(&self) -> &str {
        "Finds a program file, alias or custom command."
    }

    async fn run(&self, args: CommandArgs) -> Result<OutputStream, ShellError> {
        which(args).await
    }
}

/// Shortcuts for creating an entry to the output table
fn entry(arg: impl Into<String>, path: Value, builtin: bool, tag: Tag) -> Value {
    let mut map = IndexMap::new();
    map.insert(
        "arg".to_string(),
        UntaggedValue::Primitive(Primitive::String(arg.into())).into_value(tag.clone()),
    );
    map.insert("path".to_string(), path);
    map.insert(
        "builtin".to_string(),
        UntaggedValue::boolean(builtin).into_value(tag.clone()),
    );

    UntaggedValue::row(map).into_value(tag)
}

macro_rules! create_entry {
    ($arg:expr, $path:expr, $tag:expr, $is_builtin:expr) => {
        entry(
            $arg.clone(),
            UntaggedValue::Primitive(Primitive::String($path.to_string())).into_value($tag.clone()),
            $is_builtin,
            $tag,
        )
    };
}

fn get_entries_in_aliases(scope: &Scope, name: &str, tag: Tag) -> Vec<Value> {
    let aliases = scope
        .get_aliases_with_name(name)
        .unwrap_or_default()
        .into_iter()
        .map(|_| create_entry!(name, "Nushell alias", tag.clone(), false))
        .collect::<Vec<_>>();
    trace!("Found {} aliases", aliases.len());
    aliases
}

fn get_entries_in_custom_command(scope: &Scope, name: &str, tag: Tag) -> Vec<Value> {
    scope
        .get_custom_commands_with_name(name)
        .unwrap_or_default()
        .into_iter()
        .map(|_| create_entry!(name, "Nushell custom command", tag.clone(), false))
        .collect()
}

fn get_entry_in_commands(scope: &Scope, name: &str, tag: Tag) -> Option<Value> {
    if scope.has_command(name) {
        Some(create_entry!(name, "Nushell built-in command", tag, true))
    } else {
        None
    }
}

fn get_entries_in_nu(
    scope: &Scope,
    name: &str,
    tag: Tag,
    skip_after_first_found: bool,
) -> Vec<Value> {
    let mut all_entries = vec![];

    all_entries.extend(get_entries_in_aliases(scope, name, tag.clone()));
    if !all_entries.is_empty() && skip_after_first_found {
        return all_entries;
    }

    all_entries.extend(get_entries_in_custom_command(scope, name, tag.clone()));
    if !all_entries.is_empty() && skip_after_first_found {
        return all_entries;
    }

    if let Some(entry) = get_entry_in_commands(scope, name, tag) {
        all_entries.push(entry);
    }

    all_entries
}

#[allow(unused)]
macro_rules! entry_path {
    ($arg:expr, $path:expr, $tag:expr) => {
        entry(
            $arg.clone(),
            UntaggedValue::Primitive(Primitive::FilePath($path)).into_value($tag.clone()),
            false,
            $tag,
        )
    };
}

#[cfg(feature = "ichwh")]
async fn get_first_entry_in_path(item: &str, tag: Tag) -> Option<Value> {
    ichwh::which(item)
        .await
        .unwrap_or(None)
        .map(|path| entry_path!(item, path.into(), tag))
}

#[cfg(not(feature = "ichwh"))]
async fn get_first_entry_in_path(_: &str, _: Tag) -> Option<Value> {
    None
}

#[cfg(feature = "ichwh")]
async fn get_all_entries_in_path(item: &str, tag: Tag) -> Vec<Value> {
    ichwh::which_all(&item)
        .await
        .unwrap_or_default()
        .into_iter()
        .map(|path| entry_path!(item, path.into(), tag.clone()))
        .collect()
}

#[cfg(not(feature = "ichwh"))]
async fn get_all_entries_in_path(_: &str, _: Tag) -> Vec<Value> {
    vec![]
}

#[derive(Deserialize, Debug)]
struct WhichArgs {
    application: Tagged<String>,
    all: bool,
}

async fn which(args: CommandArgs) -> Result<OutputStream, ShellError> {
    let scope = args.scope.clone();

    let (WhichArgs { application, all }, _) = args.process().await?;

    let (external, prog_name) = if application.starts_with('^') {
        (true, application.item[1..].to_string())
    } else {
        (false, application.item.clone())
    };

    let mut output = vec![];

    //If prog_name is an external command, don't search for nu-specific programs
    //If all is false, we can save some time by only searching for the first matching
    //program
    //This match handles all different cases
    match (all, external) {
        (true, true) => {
            output.extend(get_all_entries_in_path(&prog_name, application.tag.clone()).await);
        }
        (true, false) => {
            output.extend(get_entries_in_nu(
                &scope,
                &prog_name,
                application.tag.clone(),
                false,
            ));
            output.extend(get_all_entries_in_path(&prog_name, application.tag.clone()).await);
        }
        (false, true) => {
            if let Some(entry) = get_first_entry_in_path(&prog_name, application.tag.clone()).await
            {
                output.push(entry);
            }
        }
        (false, false) => {
            let nu_entries = get_entries_in_nu(&scope, &prog_name, application.tag.clone(), true);
            if !nu_entries.is_empty() {
                output.push(nu_entries[0].clone());
            } else if let Some(entry) =
                get_first_entry_in_path(&prog_name, application.tag.clone()).await
            {
                output.push(entry);
            }
        }
    }
    Ok(futures::stream::iter(output.into_iter().map(ReturnSuccess::value)).to_output_stream())
}

#[cfg(test)]
mod tests {
    use super::ShellError;
    use super::Which;

    #[test]
    fn examples_work_as_expected() -> Result<(), ShellError> {
        use crate::examples::test as test_examples;

        Ok(test_examples(Which {})?)
    }
}