//! Place captured game windows: stacked, equal grid, or one big + a strip of minions.

use crate::hypr::{self, Client};
use crate::profile::{Layout, LayoutPreset, LayoutSlot, Profile};
use anyhow::Result;
use serde::Deserialize;

#[derive(Debug, Clone, Deserialize)]
pub struct Monitor {
    pub name: String,
    pub x: i32,
    pub y: i32,
    pub width: i32,
    pub height: i32,
}

pub async fn monitors() -> Result<Vec<Monitor>> {
    let raw = hypr::hyprctl(["-j", "monitors"]).await?;
    Ok(serde_json::from_str(&raw)?)
}

fn pick_monitor<'a>(mons: &'a [Monitor], name: &str) -> &'a Monitor {
    if !name.is_empty() {
        if let Some(m) = mons.iter().find(|m| m.name == name) {
            return m;
        }
    }
    mons.iter()
        .max_by_key(|m| m.width as i64 * m.height as i64)
        .unwrap_or(&mons[0])
}

fn split_for_n(n: u32) -> (u32, u32) {
    let n = n.max(1);
    let mut y = (n as f64).sqrt().floor() as u32;
    y = y.max(1);
    let mut x = (n as f64).sqrt().ceil() as u32;
    x = x.max(1);
    while x * y < n {
        y += 1;
    }
    (x, y)
}

pub fn generate(layout: &Layout, n: u32, mons: &[Monitor]) -> Vec<LayoutSlot> {
    if mons.is_empty() || n == 0 {
        return vec![];
    }
    let m = pick_monitor(mons, &layout.monitor);
    let mut out = match layout.preset {
        LayoutPreset::Stacked => {
            let (w, h) = constrain(m.width, m.height);
            (0..n)
                .map(|_| LayoutSlot {
                    x: m.x,
                    y: m.y,
                    w,
                    h,
                    pin: layout.pin,
                    ..Default::default()
                })
                .collect()
        }
        LayoutPreset::Grid => grid(m, n, layout.pin),
        LayoutPreset::MainStrip => main_strip(m, n, layout),
    };
    for s in &mut out {
        clamp_to_monitor(s, m);
    }
    out
}

fn clamp_to_monitor(s: &mut LayoutSlot, m: &Monitor) {
    s.w = s.w.clamp(64, m.width.max(64));
    s.h = s.h.clamp(64, m.height.max(64));
    let max_x = m.x + m.width - s.w;
    let max_y = m.y + m.height - s.h;
    s.x = s.x.clamp(m.x.min(max_x), max_x.max(m.x));
    s.y = s.y.clamp(m.y.min(max_y), max_y.max(m.y));
}

fn constrain(w: i32, h: i32) -> (i32, i32) {
    (w.max(1), h.max(1))
}

fn grid(m: &Monitor, n: u32, pin: bool) -> Vec<LayoutSlot> {
    let (cols, rows) = split_for_n(n);
    let ww = m.width / cols as i32;
    let wh = m.height / rows as i32;
    let mut out = Vec::new();
    for y in 0..rows {
        for x in 0..cols {
            if out.len() as u32 >= n {
                break;
            }
            out.push(LayoutSlot {
                x: m.x + x as i32 * ww,
                y: m.y + y as i32 * wh,
                w: ww,
                h: wh,
                pin,
                ..Default::default()
            });
        }
    }
    out
}

fn main_strip(m: &Monitor, n: u32, layout: &Layout) -> Vec<LayoutSlot> {
    if n <= 1 {
        return grid(m, n, layout.pin);
    }
    let small_n = n - 1;
    let (bw, bh, strip_h, strip_w, horizontal) = if layout.one_row {
        let c = small_n as i32;
        // wide monitor: strip along the bottom (or top)
        let bh = (m.height as f64 * c as f64 / (c + 1) as f64).round() as i32;
        (m.width, bh, m.height - bh, m.width, true)
    } else {
        let c = (n as i32 - 2).max(2);
        let bw = (m.width as f64 * c as f64 / (c + 1) as f64).round() as i32;
        let bh = (m.height as f64 * c as f64 / (c + 1) as f64).round() as i32;
        (bw, bh, m.height - bh, m.width - bw, false)
    };
    let mut out = Vec::new();
    let main_y = if layout.main_at_bottom {
        m.y + (m.height - bh)
    } else {
        m.y
    };
    out.push(LayoutSlot {
        x: m.x,
        y: main_y,
        w: bw,
        h: bh,
        pin: true, ..Default::default()
    });
    let sw = if horizontal {
        m.width / small_n.max(1) as i32
    } else {
        strip_w.max(1)
    };
    let sh = if horizontal {
        strip_h.max(1)
    } else {
        bh / small_n.max(1) as i32
    };
    let strip_y = if layout.main_at_bottom { m.y } else { m.y + bh };
    for i in 0..small_n {
        let (x, y) = if horizontal {
            (m.x + i as i32 * sw, strip_y)
        } else {
            (m.x + bw, m.y + i as i32 * sh)
        };
        out.push(LayoutSlot {
            x,
            y,
            w: sw.max(1),
            h: sh.max(1),
            pin: layout.pin,
            ..Default::default()
        });
    }
    out
}

// Item 3: select_windows is now a placeholder. The real picker
// runs in `session::refresh_slots` against `Session.spawned_pids`.
// This stub returns the first `profile.slots` visible clients in
// z-order so layout code that still calls select_windows during
// the rest of the Item 3 rollout does not silently lose every
// window. It will be deleted once refresh_slots fully owns slot
// assignment.
pub fn select_windows(_profile: &Profile, clients: Vec<Client>) -> Vec<(u32, Client)> {
    let mut visible: Vec<Client> = clients
        .into_iter()
        .filter(|c| c.mapped && !c.hidden && c.class != "enboxer-vfx")
        .collect();
    visible.sort_by_key(|c| (c.at[1], c.at[0], c.pid));
    visible
        .into_iter()
        .take(_profile.slots as usize)
        .enumerate()
        .map(|(i, c)| ((i as u32) + 1, c))
        .collect()
}

/// Window move/resize/pin is off unless ENBOXER_ALLOW_LAYOUT=1.
pub fn moves_allowed() -> bool {
    std::env::var("ENBOXER_ALLOW_LAYOUT")
        .map(|v| v == "1" || v.eq_ignore_ascii_case("true"))
        .unwrap_or(false)
}

pub async fn apply_for_profile(profile: &mut Profile) -> Result<usize> {
    if !moves_allowed() {
        anyhow::bail!("layout moves disabled (set ENBOXER_ALLOW_LAYOUT=1)");
    }
    let mons = monitors().await?;
    if profile.layout.slots.len() as u32 != profile.slots {
        profile.layout.slots = generate(&profile.layout, profile.slots, &mons);
    }
    let clients = hypr::clients().await?;
    let windows = select_windows(profile, clients);
    apply(&profile.layout.slots, &windows).await?;
    Ok(windows.len())
}

pub async fn apply(slots: &[LayoutSlot], windows: &[(u32, Client)]) -> Result<()> {
    if !moves_allowed() {
        anyhow::bail!("layout moves disabled (set ENBOXER_ALLOW_LAYOUT=1)");
    }
    let mons = monitors().await.unwrap_or_default();
    for (i, win) in windows {
        let Some(geom0) = slots.get((*i as usize).saturating_sub(1)) else {
            continue;
        };
        let mut geom = geom0.clone();
        if let Some(m) = mons.iter().find(|m| {
            geom.x >= m.x && geom.y >= m.y && geom.x < m.x + m.width && geom.y < m.y + m.height
        }) {
            clamp_to_monitor(&mut geom, m);
        } else if let Some(m) = mons.first() {
            clamp_to_monitor(&mut geom, m);
        }
        if geom.w < 64 || geom.h < 64 {
            continue;
        }
        let sel = win.address_selector();
        hypr::dispatch_lua(&format!(
            "hl.dsp.window.float({{ window = {sel:?}, action = \"on\" }})"
        ))
        .await
        .ok();
        hypr::move_resize_window(&sel, geom.x, geom.y, geom.w, geom.h).await?;
        let pin = if geom.pin { "on" } else { "off" };
        hypr::dispatch_lua(&format!(
            "hl.dsp.window.pin({{ window = {sel:?}, action = {pin:?} }})"
        ))
        .await
        .ok();
    }
    Ok(())
}

pub fn capture_from(windows: &[(u32, Client)]) -> Vec<LayoutSlot> {
    let mut out = Vec::new();
    for (_, c) in windows {
        out.push(LayoutSlot {
            x: c.at[0],
            y: c.at[1],
            w: c.size[0],
            h: c.size[1],
            pin: false,
            ..Default::default()
        });
    }
    out
}

/// Swap geometry of slot `n` with slot 1 (the main tile).
pub fn swap_main(slots: &mut [LayoutSlot], n: usize) {
    if n == 0 || n >= slots.len() {
        return;
    }
    slots.swap(0, n);
}

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

    fn mon() -> Monitor {
        Monitor {
            name: "DP-1".into(),
            x: 0,
            y: 0,
            width: 1920,
            height: 1080,
        }
    }

    #[test]
    fn stacked_same_rect() {
        let l = Layout {
            preset: LayoutPreset::Stacked,
            ..Default::default()
        };
        let s = generate(&l, 3, &[mon()]);
        assert_eq!(s.len(), 3);
        assert!(s
            .iter()
            .all(|w| w.w == 1920 && w.h == 1080 && w.x == 0 && w.y == 0));
    }

    #[test]
    fn moves_allowed_defaults_off() {
        std::env::remove_var("ENBOXER_ALLOW_LAYOUT");
        assert!(!moves_allowed());
        std::env::set_var("ENBOXER_ALLOW_LAYOUT", "1");
        assert!(moves_allowed());
        std::env::remove_var("ENBOXER_ALLOW_LAYOUT");
    }

    #[test]
    fn clamp_rejects_negative() {
        let m = mon();
        let mut s = LayoutSlot {
            x: -400,
            y: -500,
            w: 1440,
            h: 1440,
            pin: false,
            ..Default::default()
        };
        clamp_to_monitor(&mut s, &m);
        assert!(s.x >= 0 && s.y >= 0);
        assert!(s.x + s.w <= m.width);
        assert!(s.y + s.h <= m.height);
    }

    #[test]
    fn grid_five() {
        let l = Layout {
            preset: LayoutPreset::Grid,
            ..Default::default()
        };
        let s = generate(&l, 5, &[mon()]);
        assert_eq!(s.len(), 5);
        assert!(s.iter().all(|w| w.w > 0 && w.h > 0));
    }

    #[test]
    fn swap_main_exchanges_first() {
        let mut s = vec![
            LayoutSlot {
                x: 0,
                y: 0,
                w: 100,
                h: 100,
                pin: true,
                ..Default::default()
            },
            LayoutSlot {
                x: 100,
                y: 0,
                w: 50,
                h: 50,
                pin: false,
                ..Default::default()
            },
        ];
        swap_main(&mut s, 1);
        assert_eq!(s[0].w, 50);
        assert_eq!(s[1].w, 100);
    }

    #[test]
    fn main_strip_has_big_first() {
        let l = Layout {
            preset: LayoutPreset::MainStrip,
            one_row: true,
            ..Default::default()
        };
        let s = generate(&l, 4, &[mon()]);
        assert_eq!(s.len(), 4);
        assert!(s[0].w * s[0].h > s[1].w * s[1].h);
    }

    #[tokio::test]
    async fn apply_short_circuits_when_layout_disallowed() {
        // T12: apply_layout must short-circuit when ENBOXER_ALLOW_LAYOUT is unset
        // (or anything other than "1"/"true"). It must NOT touch hyprctl.
        std::env::remove_var("ENBOXER_ALLOW_LAYOUT");
        let err = apply(&[], &[]).await.unwrap_err();
        assert!(err.to_string().contains("ENBOXER_ALLOW_LAYOUT"));

        std::env::set_var("ENBOXER_ALLOW_LAYOUT", "0");
        let err = apply(&[], &[]).await.unwrap_err();
        assert!(err.to_string().contains("ENBOXER_ALLOW_LAYOUT"));

        std::env::remove_var("ENBOXER_ALLOW_LAYOUT");
    }
}