// Copyright (C) 2026 Danilo M. <danix@danix.xyz>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License version 2 as
// published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

pragma Singleton

import Quickshell
import Quickshell.Io
import QtQuick

// Everything that talks to libvirt. Shelling out to virsh rather than binding
// libvirt: the commands are the same ones the old rofi script used, and this
// adds no dependency.
Singleton {
    id: root

    // name -> { state, cpu, memUsed, memTotal, fsUsed, fsTotal, ip, vcpus, agent }
    property var vms: ({})
    property var names: []
    property var snapshots: ({})   // name -> [{ name, created, state, current }]

    // Polling only runs while the panel is open; the event stream always does.
    property bool sampling: false

    signal actionFailed(string vm, string action, string message)

    function _vm(name) {
        return vms[name] ?? { state: "unknown", cpu: -1, memUsed: -1, memTotal: -1,
                              fsUsed: -1, fsTotal: -1, ip: "", vcpus: 0, agent: false };
    }

    function _set(name, fields) {
        const next = Object.assign({}, vms);
        next[name] = Object.assign({}, _vm(name), fields);
        vms = next;
    }

    // --- discovery -------------------------------------------------------

    Process {
        id: listProc
        command: ["virsh", "list", "--all", "--name"]
        stdout: StdioCollector {
            onStreamFinished: {
                const found = text.trim().split("\n").map(s => s.trim()).filter(s => s.length);
                root.names = found;
                for (const n of found) if (!(n in root.vms)) root._set(n, {});
                root.refresh();
            }
        }
    }

    // --- state + stats ---------------------------------------------------

    // cpu.time is cumulative nanoseconds, so a percentage needs two samples.
    property var _lastCpu: ({})

    Process {
        id: statsProc
        command: ["virsh", "domstats", "--state", "--cpu-total", "--balloon", "--vcpu"]
        stdout: StdioCollector {
            onStreamFinished: {
                const now = Date.now();
                let vm = null;
                for (const line of text.split("\n")) {
                    const dom = line.match(/^Domain: '(.+)'$/);
                    if (dom) { vm = dom[1]; continue; }
                    if (!vm) continue;
                    const kv = line.trim().match(/^([\w.]+)=(.+)$/);
                    if (!kv) continue;
                    const [, key, val] = kv;

                    if (key === "state.state") {
                        root._set(vm, { state: root._stateName(parseInt(val)) });
                    } else if (key === "vcpu.current") {
                        root._set(vm, { vcpus: parseInt(val) });
                    } else if (key === "cpu.time") {
                        const ns = parseInt(val);
                        const prev = root._lastCpu[vm];
                        if (prev && now > prev.at) {
                            const vcpus = root._vm(vm).vcpus || 1;
                            const pct = (ns - prev.ns) / ((now - prev.at) * 1e6) / vcpus * 100;
                            root._set(vm, { cpu: Math.max(0, Math.min(100, pct)) });
                        }
                        const c = Object.assign({}, root._lastCpu);
                        c[vm] = { ns: ns, at: now };
                        root._lastCpu = c;
                    }
                }
                root._pollAgents();
            }
        }
    }

    function _stateName(n) {
        // libvirt VIR_DOMAIN_* enum
        return ({ 1: "running", 2: "blocked", 3: "paused", 4: "shutting down",
                  5: "shut off", 6: "crashed", 7: "suspended" })[n] ?? "unknown";
    }

    // --- guest agent -----------------------------------------------------
    //
    // Memory, filesystem usage and IP all come from qemu-guest-agent. It is
    // not up while the VM boots, and a VM may not have it at all, so every
    // one of these failing is ordinary: the rows show a dash rather than
    // falling back to a host-side number that means something different.

    property var _agentQueue: []

    function _pollAgents() {
        _agentQueue = names.filter(n => _vm(n).state === "running");
        _nextAgent();
    }

    function _nextAgent() {
        if (_agentQueue.length === 0) return;
        const vm = _agentQueue[0];
        _agentQueue = _agentQueue.slice(1);
        memProc.vm = vm;
        memProc.command = ["virsh", "dommemstat", vm];
        memProc.running = true;
    }

    Process {
        id: memProc
        property string vm: ""
        stdout: StdioCollector {
            onStreamFinished: {
                const get = k => {
                    const m = text.match(new RegExp("^" + k + " (\\d+)$", "m"));
                    return m ? parseInt(m[1]) * 1024 : -1;
                };
                const total = get("actual"), usable = get("usable");
                if (total > 0 && usable > 0) {
                    memProc.vmSet({ memUsed: total - usable, memTotal: total, agent: true });
                } else {
                    memProc.vmSet({ memUsed: -1, memTotal: total, agent: false });
                }
                fsProc.vm = memProc.vm;
                fsProc.command = ["virsh", "qemu-agent-command", memProc.vm,
                                  '{"execute":"guest-get-fsinfo"}'];
                fsProc.running = true;
            }
        }
        function vmSet(f) { root._set(vm, f); }
        onExited: code => { if (code !== 0) root._set(vm, { agent: false, memUsed: -1 }); }
    }

    Process {
        id: fsProc
        property string vm: ""
        stdout: StdioCollector {
            onStreamFinished: {
                try {
                    const fs = JSON.parse(text).return;
                    // The root filesystem is the one worth showing; the ESP is noise.
                    const r = fs.find(f => f.mountpoint === "/") ?? fs[0];
                    if (r && r["total-bytes"] > 0)
                        root._set(fsProc.vm, { fsUsed: r["used-bytes"], fsTotal: r["total-bytes"] });
                } catch (e) {
                    root._set(fsProc.vm, { fsUsed: -1, fsTotal: -1 });
                }
                ipProc.vm = fsProc.vm;
                ipProc.command = ["virsh", "domifaddr", fsProc.vm, "--source", "agent"];
                ipProc.running = true;
            }
        }
        onExited: code => { if (code !== 0) root._set(vm, { fsUsed: -1, fsTotal: -1 }); }
    }

    Process {
        id: ipProc
        property string vm: ""
        stdout: StdioCollector {
            onStreamFinished: {
                // Skip loopback and link-local; the first real v4 address wins.
                const m = text.match(/\s(\d+\.\d+\.\d+\.\d+)\/\d+/g) ?? [];
                const ip = m.map(s => s.trim().split("/")[0])
                            .find(a => !a.startsWith("127.")) ?? "";
                root._set(ipProc.vm, { ip: ip });
                root._nextAgent();
            }
        }
        onExited: code => { if (code !== 0) { root._set(vm, { ip: "" }); root._nextAgent(); } }
    }

    // --- snapshots -------------------------------------------------------

    Process {
        id: snapProc
        property string vm: ""
        stdout: StdioCollector {
            onStreamFinished: {
                const rows = [];
                for (const line of text.split("\n").slice(2)) {
                    // Name, then creation date and time, then state.
                    const m = line.trim().match(/^(\S+)\s+(\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2})[^\s]*\s*\S*\s+(\S+)/);
                    if (m) rows.push({ name: m[1], created: m[2], state: m[3] });
                }
                const next = Object.assign({}, root.snapshots);
                next[snapProc.vm] = rows;
                root.snapshots = next;
            }
        }
    }

    function loadSnapshots(vm) {
        snapProc.vm = vm;
        snapProc.command = ["virsh", "snapshot-list", vm];
        snapProc.running = true;
    }

    // --- actions ---------------------------------------------------------

    readonly property var _cmds: ({
        start:    v => ["virsh", "start", v],
        shutdown: v => ["virsh", "shutdown", "--mode", "acpi", "--domain", v],
        reboot:   v => ["virsh", "reboot", v],
        reset:    v => ["virsh", "reset", v],
        destroy:  v => ["virsh", "destroy", v],
        suspend:  v => ["virsh", "suspend", v],
        resume:   v => ["virsh", "resume", v],
    })

    function act(vm, action) {
        actProc.vm = vm; actProc.action = action;
        actProc.command = _cmds[action](vm);
        actProc.running = true;
    }

    function snapshotCreate(vm) {
        const ts = Qt.formatDateTime(new Date(), "ddMMyyyy_HHmmss");
        actProc.vm = vm; actProc.action = "snapshot";
        actProc.command = ["virsh", "snapshot-create-as", "--domain", vm,
                           "--name", `${vm}_${ts}`];
        actProc.running = true;
    }

    function snapshotRevert(vm, snap) {
        actProc.vm = vm; actProc.action = "revert";
        actProc.command = ["virsh", "snapshot-revert", vm, snap];
        actProc.running = true;
    }

    function snapshotDelete(vm, snap) {
        actProc.vm = vm; actProc.action = "snapshot delete";
        actProc.command = ["virsh", "snapshot-delete", vm, snap];
        actProc.running = true;
    }

    // Undefine with --remove-all-storage erases the disk image. The panel
    // requires the VM's name typed before it will call this.
    function deleteVm(vm) {
        actProc.vm = vm; actProc.action = "delete";
        actProc.command = ["sh", "-c",
            `virsh destroy ${JSON.stringify(vm)} 2>/dev/null; ` +
            `virsh undefine ${JSON.stringify(vm)} --remove-all-storage`];
        actProc.running = true;
    }

    Process {
        id: actProc
        property string vm: ""
        property string action: ""
        stderr: StdioCollector { id: actErr }
        onExited: code => {
            if (code !== 0)
                root.actionFailed(actProc.vm, actProc.action,
                                  actErr.text.trim() || `exited ${code}`);
            root.refreshList();
            if (root.snapshots[actProc.vm]) root.loadSnapshots(actProc.vm);
        }
    }

    // --- refresh ---------------------------------------------------------

    function refresh() { statsProc.running = true; }
    function refreshList() { listProc.running = true; }

    Timer {
        interval: 2000
        running: root.sampling
        repeat: true
        onTriggered: root.refresh()
    }

    // libvirt pushes lifecycle changes, so a VM started from virt-manager or
    // the CLI updates the panel too. This runs whether or not it is open,
    // which is what makes the panel correct the moment it is shown.
    Process {
        running: true
        command: ["virsh", "event", "--all", "--loop"]
        stdout: SplitParser {
            onRead: line => {
                if (/event '(lifecycle|agent-lifecycle)'/.test(line)) root.refreshList();
            }
        }
    }

    Component.onCompleted: refreshList()
}