use crate::Project;
use collections::HashMap;
use gpui::{AnyWindowHandle, Context, Entity, Model, ModelContext, WeakModel};
use settings::Settings;
use smol::channel::bounded;
use std::path::{Path, PathBuf};
use terminal::{
    terminal_settings::{self, Shell, TerminalSettings, VenvSettingsContent},
    SpawnTask, TaskState, TaskStatus, Terminal, TerminalBuilder,
};
use util::ResultExt;

// #[cfg(target_os = "macos")]
// use std::os::unix::ffi::OsStrExt;

pub struct Terminals {
    pub(crate) local_handles: Vec<WeakModel<terminal::Terminal>>,
}

impl Project {
    pub fn create_terminal(
        &mut self,
        working_directory: Option<PathBuf>,
        spawn_task: Option<SpawnTask>,
        window: AnyWindowHandle,
        cx: &mut ModelContext<Self>,
    ) -> anyhow::Result<Model<Terminal>> {
        anyhow::ensure!(
            !self.is_remote(),
            "creating terminals as a guest is not supported yet"
        );

        let is_terminal = spawn_task.is_none();
        let settings = TerminalSettings::get_global(cx);
        let python_settings = settings.detect_venv.clone();
        let (completion_tx, completion_rx) = bounded(1);

        let mut env = settings.env.clone();
        // Alacritty uses parent project's working directory when no working directory is provided
        // https://github.com/alacritty/alacritty/blob/fd1a3cc79192d1d03839f0fd8c72e1f8d0fce42e/extra/man/alacritty.5.scd?plain=1#L47-L52

        let venv_base_directory = working_directory
            .as_deref()
            .unwrap_or_else(|| Path::new(""));

        let (spawn_task, shell) = if let Some(spawn_task) = spawn_task {
            env.extend(spawn_task.env);
            // Activate minimal Python virtual environment
            if let Some(python_settings) = &python_settings.as_option() {
                self.set_python_venv_path_for_tasks(python_settings, venv_base_directory, &mut env);
            }
            (
                Some(TaskState {
                    id: spawn_task.id,
                    label: spawn_task.label,
                    status: TaskStatus::Running,
                    completion_rx,
                }),
                Shell::WithArguments {
                    program: spawn_task.command,
                    args: spawn_task.args,
                },
            )
        } else {
            (None, settings.shell.clone())
        };

        let terminal = TerminalBuilder::new(
            working_directory.clone(),
            spawn_task,
            shell,
            env,
            Some(settings.blinking.clone()),
            settings.alternate_scroll,
            settings.max_scroll_history_lines,
            window,
            completion_tx,
        )
        .map(|builder| {
            let terminal_handle = cx.new_model(|cx| builder.subscribe(cx));

            self.terminals
                .local_handles
                .push(terminal_handle.downgrade());

            let id = terminal_handle.entity_id();
            cx.observe_release(&terminal_handle, move |project, _terminal, cx| {
                let handles = &mut project.terminals.local_handles;

                if let Some(index) = handles
                    .iter()
                    .position(|terminal| terminal.entity_id() == id)
                {
                    handles.remove(index);
                    cx.notify();
                }
            })
            .detach();

            // if the terminal is not a task, activate full Python virtual environment
            if is_terminal {
                if let Some(python_settings) = &python_settings.as_option() {
                    if let Some(activate_script_path) =
                        self.find_activate_script_path(python_settings, venv_base_directory)
                    {
                        self.activate_python_virtual_environment(
                            Project::get_activate_command(python_settings),
                            activate_script_path,
                            &terminal_handle,
                            cx,
                        );
                    }
                }
            }
            terminal_handle
        });

        terminal
    }

    pub fn find_activate_script_path(
        &mut self,
        settings: &VenvSettingsContent,
        venv_base_directory: &Path,
    ) -> Option<PathBuf> {
        let activate_script_name = match settings.activate_script {
            terminal_settings::ActivateScript::Default => "activate",
            terminal_settings::ActivateScript::Csh => "activate.csh",
            terminal_settings::ActivateScript::Fish => "activate.fish",
            terminal_settings::ActivateScript::Nushell => "activate.nu",
        };

        settings
            .directories
            .into_iter()
            .find_map(|virtual_environment_name| {
                let path = venv_base_directory
                    .join(virtual_environment_name)
                    .join("bin")
                    .join(activate_script_name);
                path.exists().then_some(path)
            })
    }

    pub fn set_python_venv_path_for_tasks(
        &mut self,
        settings: &VenvSettingsContent,
        venv_base_directory: &Path,
        env: &mut HashMap<String, String>,
    ) {
        let activate_path = settings
            .directories
            .into_iter()
            .find_map(|virtual_environment_name| {
                let path = venv_base_directory.join(virtual_environment_name);
                path.exists().then_some(path)
            });

        if let Some(path) = activate_path {
            // Some tools use VIRTUAL_ENV to detect the virtual environment
            env.insert(
                "VIRTUAL_ENV".to_string(),
                path.to_string_lossy().to_string(),
            );

            let path_bin = path.join("bin");
            // We need to set the PATH to include the virtual environment's bin directory
            if let Some(paths) = std::env::var_os("PATH") {
                let paths = std::iter::once(path_bin).chain(std::env::split_paths(&paths));
                if let Some(new_path) = std::env::join_paths(paths).log_err() {
                    env.insert("PATH".to_string(), new_path.to_string_lossy().to_string());
                }
            } else {
                env.insert(
                    "PATH".to_string(),
                    path.join("bin").to_string_lossy().to_string(),
                );
            }
        }
    }

    fn get_activate_command(settings: &VenvSettingsContent) -> &'static str {
        match settings.activate_script {
            terminal_settings::ActivateScript::Nushell => "overlay use",
            _ => "source",
        }
    }

    fn activate_python_virtual_environment(
        &mut self,
        activate_command: &'static str,
        activate_script: PathBuf,
        terminal_handle: &Model<Terminal>,
        cx: &mut ModelContext<Project>,
    ) {
        // Paths are not strings so we need to jump through some hoops to format the command without `format!`
        let mut command = Vec::from(activate_command.as_bytes());
        command.push(b' ');
        // Wrapping path in double quotes to catch spaces in folder name
        command.extend_from_slice(b"\"");
        command.extend_from_slice(activate_script.as_os_str().as_encoded_bytes());
        command.extend_from_slice(b"\"");
        command.push(b'\n');

        terminal_handle.update(cx, |this, _| this.input_bytes(command));
    }

    pub fn local_terminal_handles(&self) -> &Vec<WeakModel<terminal::Terminal>> {
        &self.terminals.local_handles
    }
}

// TODO: Add a few tests for adding and removing terminal tabs