use agent_client_protocol as acp;

use futures::{FutureExt as _, future::Shared};
use gpui::{App, AppContext, Context, Entity, Task};
use language::LanguageRegistry;
use markdown::Markdown;
use std::{path::PathBuf, process::ExitStatus, sync::Arc, time::Instant};

pub struct Terminal {
    id: acp::TerminalId,
    command: Entity<Markdown>,
    working_dir: Option<PathBuf>,
    terminal: Entity<terminal::Terminal>,
    started_at: Instant,
    output: Option<TerminalOutput>,
    output_byte_limit: Option<usize>,
    _output_task: Shared<Task<acp::TerminalExitStatus>>,
}

pub struct TerminalOutput {
    pub ended_at: Instant,
    pub exit_status: Option<ExitStatus>,
    pub content: String,
    pub original_content_len: usize,
    pub content_line_count: usize,
}

impl Terminal {
    pub fn new(
        id: acp::TerminalId,
        command: String,
        working_dir: Option<PathBuf>,
        output_byte_limit: Option<usize>,
        terminal: Entity<terminal::Terminal>,
        language_registry: Arc<LanguageRegistry>,
        cx: &mut Context<Self>,
    ) -> Self {
        let command_task = terminal.read(cx).wait_for_completed_task(cx);
        Self {
            id,
            command: cx.new(|cx| {
                Markdown::new(
                    format!("```\n{}\n```", command).into(),
                    Some(language_registry.clone()),
                    None,
                    cx,
                )
            }),
            working_dir,
            terminal,
            started_at: Instant::now(),
            output: None,
            output_byte_limit,
            _output_task: cx
                .spawn(async move |this, cx| {
                    let exit_status = command_task.await;

                    this.update(cx, |this, cx| {
                        let (content, original_content_len) = this.truncated_output(cx);
                        let content_line_count = this.terminal.read(cx).total_lines();

                        this.output = Some(TerminalOutput {
                            ended_at: Instant::now(),
                            exit_status,
                            content,
                            original_content_len,
                            content_line_count,
                        });
                        cx.notify();
                    })
                    .ok();

                    let exit_status = exit_status.map(portable_pty::ExitStatus::from);

                    acp::TerminalExitStatus {
                        exit_code: exit_status.as_ref().map(|e| e.exit_code()),
                        signal: exit_status.and_then(|e| e.signal().map(Into::into)),
                    }
                })
                .shared(),
        }
    }

    pub fn id(&self) -> &acp::TerminalId {
        &self.id
    }

    pub fn wait_for_exit(&self) -> Shared<Task<acp::TerminalExitStatus>> {
        self._output_task.clone()
    }

    pub fn kill(&mut self, cx: &mut App) {
        self.terminal.update(cx, |terminal, _cx| {
            terminal.kill_active_task();
        });
    }

    pub fn current_output(&self, cx: &App) -> acp::TerminalOutputResponse {
        if let Some(output) = self.output.as_ref() {
            let exit_status = output.exit_status.map(portable_pty::ExitStatus::from);

            acp::TerminalOutputResponse {
                output: output.content.clone(),
                truncated: output.original_content_len > output.content.len(),
                exit_status: Some(acp::TerminalExitStatus {
                    exit_code: exit_status.as_ref().map(|e| e.exit_code()),
                    signal: exit_status.and_then(|e| e.signal().map(Into::into)),
                }),
            }
        } else {
            let (current_content, original_len) = self.truncated_output(cx);

            acp::TerminalOutputResponse {
                truncated: current_content.len() < original_len,
                output: current_content,
                exit_status: None,
            }
        }
    }

    fn truncated_output(&self, cx: &App) -> (String, usize) {
        let terminal = self.terminal.read(cx);
        let mut content = terminal.get_content();

        let original_content_len = content.len();

        if let Some(limit) = self.output_byte_limit
            && content.len() > limit
        {
            let mut end_ix = limit.min(content.len());
            while !content.is_char_boundary(end_ix) {
                end_ix -= 1;
            }
            // Don't truncate mid-line, clear the remainder of the last line
            end_ix = content[..end_ix].rfind('\n').unwrap_or(end_ix);
            content.truncate(end_ix);
        }

        (content, original_content_len)
    }

    pub fn command(&self) -> &Entity<Markdown> {
        &self.command
    }

    pub fn working_dir(&self) -> &Option<PathBuf> {
        &self.working_dir
    }

    pub fn started_at(&self) -> Instant {
        self.started_at
    }

    pub fn output(&self) -> Option<&TerminalOutput> {
        self.output.as_ref()
    }

    pub fn inner(&self) -> &Entity<terminal::Terminal> {
        &self.terminal
    }

    pub fn to_markdown(&self, cx: &App) -> String {
        format!(
            "Terminal:\n```\n{}\n```\n",
            self.terminal.read(cx).get_content()
        )
    }
}