use super::{api_helpers::pane_agent_status, App};

#[derive(Debug, Clone, PartialEq, Eq)]
pub(crate) struct TerminalTarget {
    pub ws_idx: usize,
    pub tab_idx: usize,
    pub pane_id: crate::layout::PaneId,
    pub terminal_id: String,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub(crate) struct TerminalTargetCandidate {
    pub terminal_id: String,
    pub pane_id: String,
    pub workspace_id: String,
    pub tab_id: String,
    pub cwd: Option<String>,
    pub agent_status: crate::api::schema::AgentStatus,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub(crate) enum TerminalTargetError {
    NotFound {
        target: String,
    },
    Ambiguous {
        target: String,
        candidates: Vec<TerminalTargetCandidate>,
    },
}

impl App {
    pub(crate) fn resolve_terminal_target(
        &self,
        target: &str,
    ) -> Result<TerminalTarget, TerminalTargetError> {
        let terminal_matches: Vec<_> = self
            .terminal_targets()
            .into_iter()
            .filter(|candidate| candidate.terminal_id == target)
            .collect();
        if let Some(resolved) = self.single_terminal_match(target, terminal_matches)? {
            return Ok(resolved);
        }

        if let Some((ws_idx, pane_id)) = self.parse_current_public_pane_id(target) {
            if let Some(resolved) = self.terminal_target_for_pane(ws_idx, pane_id) {
                return Ok(resolved);
            }
        }

        let agent_matches: Vec<_> = self
            .terminal_targets()
            .into_iter()
            .filter(|candidate| {
                self.state
                    .terminals
                    .get(candidate.terminal_id.as_str())
                    .is_some_and(|terminal| {
                        terminal.agent_name.as_deref() == Some(target)
                            || terminal.effective_agent_label() == Some(target)
                    })
            })
            .collect();
        if let Some(resolved) = self.single_terminal_match(target, agent_matches)? {
            return Ok(resolved);
        }

        Err(TerminalTargetError::NotFound {
            target: target.to_string(),
        })
    }

    pub(crate) fn resolve_agent_target(
        &self,
        target: &str,
    ) -> Result<TerminalTarget, TerminalTargetError> {
        if let Some((ws_idx, pane_id)) = self.parse_current_public_pane_id(target) {
            if let Some(resolved) = self
                .terminal_target_for_pane(ws_idx, pane_id)
                .filter(|resolved| self.target_is_agent(resolved))
            {
                return Ok(resolved);
            }
        }

        let name_matches: Vec<_> = self
            .terminal_targets()
            .into_iter()
            .filter(|candidate| {
                self.state
                    .terminals
                    .get(candidate.terminal_id.as_str())
                    .is_some_and(|terminal| terminal.agent_name.as_deref() == Some(target))
            })
            .collect();
        if let Some(resolved) = self.single_terminal_match(target, name_matches)? {
            return Ok(resolved);
        }

        Err(TerminalTargetError::NotFound {
            target: target.to_string(),
        })
    }

    fn target_is_agent(&self, target: &TerminalTarget) -> bool {
        self.state
            .terminals
            .get(target.terminal_id.as_str())
            .is_some_and(|terminal| terminal.is_agent_terminal())
    }

    fn single_terminal_match(
        &self,
        target: &str,
        matches: Vec<TerminalTarget>,
    ) -> Result<Option<TerminalTarget>, TerminalTargetError> {
        match matches.len() {
            0 => Ok(None),
            1 => Ok(matches.into_iter().next()),
            _ => Err(TerminalTargetError::Ambiguous {
                target: target.to_string(),
                candidates: matches
                    .into_iter()
                    .filter_map(|candidate| {
                        self.terminal_target_candidate(candidate.ws_idx, candidate.pane_id)
                    })
                    .collect(),
            }),
        }
    }

    fn terminal_targets(&self) -> Vec<TerminalTarget> {
        self.state
            .workspaces
            .iter()
            .enumerate()
            .flat_map(|(ws_idx, ws)| {
                ws.tabs.iter().enumerate().flat_map(move |(tab_idx, tab)| {
                    tab.layout
                        .pane_ids()
                        .into_iter()
                        .filter_map(move |pane_id| {
                            tab.terminal_id(pane_id).map(|terminal_id| TerminalTarget {
                                ws_idx,
                                tab_idx,
                                pane_id,
                                terminal_id: terminal_id.to_string(),
                            })
                        })
                })
            })
            .collect()
    }

    fn terminal_target_for_pane(
        &self,
        ws_idx: usize,
        pane_id: crate::layout::PaneId,
    ) -> Option<TerminalTarget> {
        let ws = self.state.workspaces.get(ws_idx)?;
        let tab_idx = ws.find_tab_index_for_pane(pane_id)?;
        let terminal_id = ws.terminal_id(pane_id)?.to_string();
        Some(TerminalTarget {
            ws_idx,
            tab_idx,
            pane_id,
            terminal_id,
        })
    }

    fn terminal_target_candidate(
        &self,
        ws_idx: usize,
        pane_id: crate::layout::PaneId,
    ) -> Option<TerminalTargetCandidate> {
        let ws = self.state.workspaces.get(ws_idx)?;
        let tab_idx = ws.find_tab_index_for_pane(pane_id)?;
        let pane = ws.pane_state(pane_id)?;
        let terminal = self.state.terminals.get(&pane.attached_terminal_id)?;
        Some(TerminalTargetCandidate {
            terminal_id: terminal.id.to_string(),
            pane_id: self.public_pane_id(ws_idx, pane_id)?,
            workspace_id: self.public_workspace_id(ws_idx),
            tab_id: self.public_tab_id(ws_idx, tab_idx)?,
            cwd: ws.tabs[tab_idx]
                .cwd_for_pane(pane_id, &self.state.terminals, &self.terminal_runtimes)
                .map(|cwd| cwd.display().to_string()),
            agent_status: pane_agent_status(terminal.state, pane.seen),
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::app::{AppPolicy, AppState};

    fn test_app() -> App {
        let (_, api_rx) = tokio::sync::mpsc::unbounded_channel();
        App::new(
            &crate::config::Config::default(),
            AppPolicy::TEST,
            None,
            api_rx,
            crate::api::EventHub::default(),
        )
    }

    #[test]
    fn named_targets_follow_terminal_identity_after_pane_and_tab_reordering() {
        let mut app = test_app();
        app.state = AppState::test_with_adversarial_identity_state();
        let targets = app.terminal_targets();
        for (index, target) in targets.iter().enumerate() {
            app.state
                .terminals
                .get_mut(target.terminal_id.as_str())
                .unwrap()
                .set_agent_name(format!("worker-{index}"));
        }
        for (index, target) in targets.iter().enumerate() {
            let name = format!("worker-{index}");
            assert_eq!(app.resolve_terminal_target(&name).unwrap(), *target);
            assert_eq!(app.resolve_agent_target(&name).unwrap(), *target);
            let pane = app.public_pane_id(target.ws_idx, target.pane_id).unwrap();
            assert_eq!(app.resolve_agent_target(&pane).unwrap(), *target);
        }
        app.state.assert_invariants_for_test();
    }

    #[test]
    fn name_lookup_keeps_pane_order_and_ignores_detached_terminals() {
        let mut app = test_app();
        app.state = AppState::test_with_adversarial_identity_state();
        let targets = app.terminal_targets();
        for target in &targets {
            app.state
                .terminals
                .get_mut(target.terminal_id.as_str())
                .unwrap()
                .set_agent_name("shared".into());
        }
        let detached_id = crate::terminal::TerminalId::alloc();
        let mut detached =
            crate::terminal::TerminalState::new(detached_id.clone(), std::env::temp_dir());
        detached.set_agent_name("detached".into());
        app.state.terminals.insert(detached_id, detached);
        assert!(matches!(
            app.resolve_agent_target("detached"),
            Err(TerminalTargetError::NotFound { .. })
        ));
        for result in [
            app.resolve_terminal_target("shared"),
            app.resolve_agent_target("shared"),
        ] {
            let Err(TerminalTargetError::Ambiguous { candidates, .. }) = result else {
                panic!("expected all attached panes to remain ambiguous");
            };
            assert_eq!(
                candidates
                    .iter()
                    .map(|candidate| candidate.terminal_id.as_str())
                    .collect::<Vec<_>>(),
                targets
                    .iter()
                    .map(|target| target.terminal_id.as_str())
                    .collect::<Vec<_>>(),
            );
        }
    }

    #[test]
    #[ignore = "manual terminal target lookup scaling profile"]
    fn terminal_target_lookup_profile() {
        use std::hint::black_box;
        use std::time::{Duration, Instant};

        for count in [1, 15, 128, 512] {
            let mut app = test_app();
            let mut workspace = crate::workspace::Workspace::test_new("lookup-profile");
            for _ in 1..count {
                workspace.test_split(ratatui::layout::Direction::Horizontal);
            }
            app.state.workspaces = vec![workspace];
            app.state.ensure_test_terminals();
            let id = app.state.workspaces[0]
                .terminal_id(app.state.workspaces[0].tabs[0].root_pane)
                .unwrap()
                .clone();
            app.state
                .terminals
                .get_mut(&id)
                .unwrap()
                .set_agent_name("profile-target".into());
            for (label, agent, target) in [
                ("terminal-name", false, "profile-target"),
                ("agent-name", true, "profile-target"),
                ("missing", false, "missing-target"),
            ] {
                let lookup = || {
                    if agent {
                        app.resolve_agent_target(target)
                    } else {
                        app.resolve_terminal_target(target)
                    }
                };
                for _ in 0..32 {
                    black_box(lookup()).ok();
                }
                let mut samples = Vec::new();
                for _ in 0..7 {
                    let start = Instant::now();
                    let mut iterations = 0;
                    while start.elapsed() < Duration::from_millis(20) {
                        black_box(lookup()).ok();
                        iterations += 1;
                    }
                    samples.push(start.elapsed().as_secs_f64() * 1e6 / f64::from(iterations));
                }
                samples.sort_by(f64::total_cmp);
                println!(
                    "terminal-target panes={count} case={label} median_us={:.3}",
                    samples[3]
                );
            }
        }
    }
}