//! Synthetic graph builders for the taint-engine tests.
//!
//! Serials are handed out monotonically and never reused, exactly as
//! PipeWire does; global ids are handed out separately and **may be reused
//! on purpose**, which is what the recycling tests need.

use std::collections::BTreeMap;

use super::snapshot::{
    ClientSnapshot, GlobalId, GraphSnapshot, LinkSnapshot, MediaRole, NodeProps, NodeSnapshot,
    PortDirection, PortSnapshot, Serial,
};

/// pipewire-pulse's PID, as measured on the target machine.
pub const PULSE_PID: u32 = 2541;
/// WirePlumber's PID — one process owning every device node on the box.
pub const SESSION_PID: u32 = 900;

/// A node's identity in a fixture: what tests pass around.
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
pub struct NodeRef {
    pub serial: Serial,
    pub id: GlobalId,
}

#[derive(Default)]
pub struct Graph {
    next_serial: u64,
    next_id: u32,
    nodes: Vec<NodeSnapshot>,
    ports: Vec<PortSnapshot>,
    links: Vec<LinkSnapshot>,
    clients: Vec<ClientSnapshot>,
    /// One client connection per process / per module, which is what the
    /// live graph looks like. Tests that need the *split*-client shape
    /// (GStreamer opens one per stream) pass clients explicitly instead.
    client_by_app: BTreeMap<u32, GlobalId>,
    client_by_module: BTreeMap<u64, GlobalId>,
    session_client: Option<GlobalId>,
}

impl Graph {
    pub fn new() -> Self {
        Self {
            // Start past u32::MAX so every fixture also exercises the phase
            // 0a widening: a serial that a u32 model would have truncated.
            next_serial: u64::from(u32::MAX) + 1,
            next_id: 1,
            ..Self::default()
        }
    }

    fn serial(&mut self) -> Serial {
        self.next_serial += 1;
        Serial(self.next_serial)
    }

    fn id(&mut self) -> GlobalId {
        self.next_id += 1;
        GlobalId(self.next_id)
    }

    /// A client object. `sec_pid` is `pipewire.sec.pid` — pipewire-pulse's
    /// PID for Pulse-emulated clients.
    pub fn client(&mut self, sec_pid: Option<u32>) -> GlobalId {
        let serial = self.serial();
        let id = self.id();
        self.clients.push(ClientSnapshot {
            serial,
            id,
            sec_pid,
        });
        id
    }

    /// The client connection an ordinary process holds — one per PID,
    /// created on demand.
    pub fn client_of_app(&mut self, pid: u32) -> GlobalId {
        if let Some(id) = self.client_by_app.get(&pid) {
            return *id;
        }
        let id = self.client(Some(PULSE_PID));
        self.client_by_app.insert(pid, id);
        id
    }

    /// An ordinary application stream: its own client, its own PID.
    pub fn app_node(&mut self, name: &str, role: MediaRole, pid: u32) -> NodeRef {
        let client = self.client_of_app(pid);
        self.node(name, role, app(client, pid))
    }

    /// The client a pactl module holds. Measured: each module gets its own
    /// (`sink-sunshine-*` were clients 83/86/92), which is why one tainted
    /// module does not fuse with the next.
    pub fn client_of_module(&mut self, module: u64) -> GlobalId {
        match self.client_by_module.get(&module) {
            Some(id) => *id,
            None => {
                let id = self.client(Some(PULSE_PID));
                self.client_by_module.insert(module, id);
                id
            }
        }
    }

    /// A leg of a pactl-loaded module: one client per module, and the
    /// node's `application.process.id` is **pipewire-pulse's own**, because
    /// pipewire-pulse genuinely is the client.
    pub fn module_node(&mut self, name: &str, role: MediaRole, module: u64) -> NodeRef {
        let client = self.client_of_module(module);
        self.node(name, role, pulse_module(client, module, PULSE_PID))
    }

    /// A leg joined to its siblings by `node.link-group` — loopback,
    /// filter-chain, echo-cancel.
    pub fn group_node(&mut self, name: &str, role: MediaRole, group: &str, pid: u32) -> NodeRef {
        let client = self.client_of_app(pid);
        self.node(name, role, link_group(group, client, pid))
    }

    /// A device node as the session manager creates it: no strong key,
    /// WirePlumber's client and PID — shared with every other device — and
    /// a `device.id`, which is what marks it as session-manager-exported.
    pub fn device_node(&mut self, name: &str, role: MediaRole) -> NodeRef {
        let session = match self.session_client {
            Some(id) => id,
            None => {
                let id = self.client(None);
                self.session_client = Some(id);
                id
            }
        };
        self.node(name, role, device(session, SESSION_PID))
    }

    /// A node that *belongs to* a Device but is not a passive device node —
    /// a filter associated with a card. Phase 3 must not classify this as a
    /// session device, or it loses both its coarse owner keys and its
    /// ability to trip the fail-closed backstop.
    pub fn device_associated_filter(&mut self, name: &str, role: MediaRole, pid: u32) -> NodeRef {
        let client = self.client_of_app(pid);
        self.node(name, role, app(client, pid))
    }

    /// A **virtual** sink an application created natively: an `Audio/Sink`
    /// with no `device.id` and no strong key, sharing one client with the
    /// stream that re-emits what it receives. Coarse keys must still bridge
    /// these two, or the whole call leaks through the re-emitting leg.
    pub fn native_virtual_node(&mut self, name: &str, role: MediaRole, pid: u32) -> NodeRef {
        let client = self.client_of_app(pid);
        self.node(name, role, app(client, pid))
    }

    /// A peerspeak-owned node carrying **both** ownership carriers, as a
    /// live one does. `name` gets the real `node.name` prefix so the fixture
    /// cannot pass on the property alone.
    pub fn peerspeak_node(&mut self, name: &str, pid: u32) -> NodeRef {
        let client = self.client_of_app(pid);
        let name = format!("{}{name}_{pid}", super::PEERSPEAK_OWNED_NODE_PREFIX);
        self.node(&name, MediaRole::StreamOutput, peerspeak_owned(client, pid))
    }

    /// Carrier 1 alone: the `peerspeak.owned` property present, the
    /// `node.name` prefix absent. What the engine sees for a node it had to
    /// bind to observe (v3.5 §6.7).
    pub fn peerspeak_node_prop_only(&mut self, name: &str, pid: u32) -> NodeRef {
        let client = self.client_of_app(pid);
        self.node(name, MediaRole::StreamOutput, peerspeak_owned(client, pid))
    }

    /// Carrier 2 alone: the `node.name` prefix present, the property absent
    /// — indistinguishable from an ordinary app in every other respect.
    /// This is the case that survives the F1 observation defect, and the
    /// reason round 8 added a second carrier at all.
    pub fn peerspeak_node_name_only(&mut self, role: &str, pid: u32) -> NodeRef {
        let client = self.client_of_app(pid);
        let name = format!("{}{role}_{pid}", super::PEERSPEAK_OWNED_NODE_PREFIX);
        self.node(&name, MediaRole::StreamOutput, app(client, pid))
    }

    pub fn node(&mut self, name: &str, role: MediaRole, props: NodeProps) -> NodeRef {
        let id = self.id();
        self.node_with_id(name, role, id, props)
    }

    /// Force a global id — for reproducing id recycling after teardown.
    pub fn node_with_id(
        &mut self,
        name: &str,
        role: MediaRole,
        id: GlobalId,
        props: NodeProps,
    ) -> NodeRef {
        let serial = self.serial();
        self.nodes.push(NodeSnapshot {
            serial,
            id,
            name: Some(name.to_string()),
            role,
            props,
        });
        NodeRef { serial, id }
    }

    pub fn port(&mut self, node: NodeRef, direction: PortDirection, exclusive: bool) {
        let serial = self.serial();
        let id = self.id();
        self.ports.push(PortSnapshot {
            serial,
            id,
            node: node.id,
            direction,
            exclusive,
            monitor: false,
        });
    }

    /// A signal edge: audio flows `from → to`.
    pub fn link(&mut self, from: NodeRef, to: NodeRef) {
        self.link_ids(from.id, to.id);
    }

    /// A link naming raw ids, so a test can dangle an endpoint.
    pub fn link_ids(&mut self, from: GlobalId, to: GlobalId) {
        let serial = self.serial();
        let id = self.id();
        self.links.push(LinkSnapshot {
            serial,
            id,
            output_node: from,
            input_node: to,
            output_port: None,
            input_port: None,
        });
    }

    /// An id that belongs to nothing — for unresolved-endpoint tests.
    pub fn dangling_id(&mut self) -> GlobalId {
        self.id()
    }

    pub fn build(&self) -> GraphSnapshot {
        self.build_without(&[])
    }

    /// A later snapshot in which some nodes have gone away, along with
    /// their ports and every link touching them. Surviving objects keep
    /// their serials, which is what makes sticky-taint sequences testable.
    pub fn build_without(&self, dropped: &[NodeRef]) -> GraphSnapshot {
        let gone_serials: Vec<Serial> = dropped.iter().map(|n| n.serial).collect();
        let nodes: Vec<NodeSnapshot> = self
            .nodes
            .iter()
            .filter(|n| !gone_serials.contains(&n.serial))
            .cloned()
            .collect();
        // Filter by what was *dropped*, not by what is live: a link to an id
        // that never had a node is a dangling endpoint, and dropping those
        // here would quietly disarm every unresolved-ancestry test.
        let gone_ids: Vec<GlobalId> = dropped.iter().map(|n| n.id).collect();
        GraphSnapshot::new(
            nodes,
            self.ports
                .iter()
                .filter(|p| !gone_ids.contains(&p.node))
                .cloned()
                .collect(),
            self.links
                .iter()
                .filter(|l| !gone_ids.contains(&l.output_node) && !gone_ids.contains(&l.input_node))
                .cloned()
                .collect(),
            self.clients.clone(),
        )
    }

    /// Drop clients too — full owner teardown.
    ///
    /// Invalidates the per-app/per-module caches as well: leaving them
    /// stale made a later `client_of_app` hand back the *removed* client's
    /// id, so a test that meant "a brand-new client after teardown" was
    /// really building a node pointing at a client object that no longer
    /// existed (Codex round 1, finding 8).
    pub fn drop_clients(&mut self, ids: &[GlobalId]) {
        self.clients.retain(|c| !ids.contains(&c.id));
        self.client_by_app.retain(|_, id| !ids.contains(id));
        self.client_by_module.retain(|_, id| !ids.contains(id));
        if self.session_client.is_some_and(|id| ids.contains(&id)) {
            self.session_client = None;
        }
    }

    /// A client that reuses a global id a dead client had — the recycling
    /// case, with a fresh serial.
    pub fn client_with_id(&mut self, id: GlobalId, sec_pid: Option<u32>) -> GlobalId {
        let serial = self.serial();
        self.clients.push(ClientSnapshot {
            serial,
            id,
            sec_pid,
        });
        id
    }
}

/// An ordinary application stream: real PID, one client connection.
pub fn app(client: GlobalId, pid: u32) -> NodeProps {
    NodeProps {
        client_id: Some(client),
        process_id: Some(pid),
        ..NodeProps::default()
    }
}

/// A pactl-module-created stream: the daemon is the client, so the node's
/// `application.process.id` is pipewire-pulse's own.
pub fn pulse_module(client: GlobalId, module: u64, pulse_pid: u32) -> NodeProps {
    NodeProps {
        pulse_module_id: Some(module),
        client_id: Some(client),
        process_id: Some(pulse_pid),
        ..NodeProps::default()
    }
}

/// A PipeWire-module leg joined to its siblings by `node.link-group`
/// (loopback, filter-chain, echo-cancel).
pub fn link_group(group: &str, client: GlobalId, pid: u32) -> NodeProps {
    NodeProps {
        link_group: Some(group.to_string()),
        client_id: Some(client),
        process_id: Some(pid),
        ..NodeProps::default()
    }
}

/// A device node as the session manager creates it: no strong key, and the
/// session manager's own client and PID — shared with every other device.
///
/// Measured 2026-07-21: real ALSA device nodes carry the shared
/// `client.id` but **no** `application.process.id` at all. Giving them one
/// here is deliberately *more* pessimistic than reality — it hands the
/// engine a second coarse key it could fuse devices on, so a test that
/// passes here also passes against the real props.
pub fn device(session_client: GlobalId, session_pid: u32) -> NodeProps {
    NodeProps {
        client_id: Some(session_client),
        process_id: Some(session_pid),
        session_device: true,
        ..NodeProps::default()
    }
}

pub fn peerspeak_owned(client: GlobalId, pid: u32) -> NodeProps {
    NodeProps {
        peerspeak_owned: true,
        ..app(client, pid)
    }
}