import QtQuick
import Flora

Canvas {
    id: g

    property var nodes: []
    property var edges: []
    signal fileClicked(string path)

    property var pos: ({})
    property string dragKey: ""
    property real zoom: 1.0
    property real panX: 0
    property real panY: 0
    property real lastMouseX: 0
    property real lastMouseY: 0
    property bool isEmpty: nodes.length === 0

    function nodeForKey(key) {
        for (let i = 0; i < nodes.length; ++i)
            if (nodes[i].key === key) return nodes[i]
        return null
    }

    function relayout() {
        const n = nodes.length
        if (n === 0) { pos = {}; requestPaint(); return }
        if (n > 600) {
            // Слишком много узлов — показываем упрощённо без симуляции чтобы не заморозить UI
            const cx = width / 2, cy = height / 2
            const rad = Math.min(width, height) / 2 - 36
            let newPos = {}
            for (let i = 0; i < n; ++i) {
                const a = (i / n) * 2 * Math.PI - Math.PI / 2
                newPos[nodes[i].key] = { x: cx + rad * Math.cos(a), y: cy + rad * Math.sin(a) }
            }
            pos = newPos; zoom = 1.0; panX = 0; panY = 0; requestPaint(); return
        }
        const cx = width / 2, cy = height / 2
        const rad = Math.min(width, height) / 2 - 36
        let newPos = {}
        for (let i = 0; i < n; ++i) {
            const a = (i / n) * 2 * Math.PI - Math.PI / 2
            // небольшой джиттер чтобы не накладывались ровно
            const jitter = (Math.random() - 0.5) * 8
            newPos[nodes[i].key] = { x: cx + rad * Math.cos(a) + jitter, y: cy + rad * Math.sin(a) + jitter }
        }
        const iterCount = n > 200 ? 25 : (n > 100 ? 40 : 80)
        // простая force-симуляция для разведения узлов (репульсия + притяжение по рёбрам)
        for (let iter = 0; iter < iterCount; ++iter) {
            // репульсия между всеми парами
            for (let i = 0; i < n; ++i) {
                for (let j = i + 1; j < n; ++j) {
                    const a = newPos[nodes[i].key]
                    const b = newPos[nodes[j].key]
                    let dx = a.x - b.x, dy = a.y - b.y
                    let dist = Math.sqrt(dx*dx + dy*dy)
                    if (dist < 1) dist = 1
                    if (dist < 70) {
                        const force = (70 - dist) * 0.08
                        const nx = dx / dist * force
                        const ny = dy / dist * force
                        a.x += nx; a.y += ny
                        b.x -= nx; b.y -= ny
                    }
                }
            }
            // притяжение по рёбрам
            for (let e = 0; e < edges.length; ++e) {
                const f = newPos[edges[e].from]
                const t = newPos[edges[e].to]
                if (!f || !t) continue
                let dx = t.x - f.x, dy = t.y - f.y
                let dist = Math.sqrt(dx*dx + dy*dy)
                if (dist < 1) continue
                const target = 90
                const force = (dist - target) * 0.02
                const nx = dx / dist * force
                const ny = dy / dist * force
                f.x += nx; f.y += ny
                t.x -= nx; t.y -= ny
            }
            // удержание в границах
            for (let k in newPos) {
                const p = newPos[k]
                p.x = Math.max(30, Math.min(width - 30, p.x))
                p.y = Math.max(30, Math.min(height - 30, p.y))
            }
        }
        pos = newPos
        zoom = 1.0; panX = 0; panY = 0
        requestPaint()
    }

    onNodesChanged: relayout()
    onWidthChanged: relayout()
    onHeightChanged: relayout()

    // пустое состояние
    Text {
        anchors.centerIn: parent
        visible: g.isEmpty
        text: qsTr("Нет связей\nДобавьте [[ссылки]] или #теги")
        color: Theme.textMuted
        horizontalAlignment: Text.AlignHCenter
        font.pixelSize: 11
        lineHeight: 1.3
    }

    function paintCanvas() {
        const ctx = getContext("2d")
        ctx.clearRect(0, 0, width, height)
        if (nodes.length === 0) return

        ctx.save()
        ctx.translate(width / 2 + panX, height / 2 + panY)
        ctx.scale(zoom, zoom)
        ctx.translate(-width / 2, -height / 2)

        ctx.lineWidth = 1 / zoom
        ctx.strokeStyle = Theme.graphEdge
        for (let i = 0; i < edges.length; ++i) {
            const f = pos[edges[i].from]
            const t = pos[edges[i].to]
            if (!f || !t) continue
            ctx.beginPath()
            ctx.moveTo(f.x, f.y)
            ctx.lineTo(t.x, t.y)
            ctx.stroke()
        }

        ctx.textAlign = "center"
        for (let i = 0; i < nodes.length; ++i) {
            const nd = nodes[i]
            const p = pos[nd.key]
            if (!p) continue
            const isFile = nd.type === "file"
            const r = isFile ? 6 : 5
            ctx.beginPath()
            ctx.arc(p.x, p.y, r, 0, 2 * Math.PI)
            if (isFile) {
                ctx.fillStyle = (nd.key === g.dragKey) ? Theme.accentHover : Theme.graphNodeFile
            } else {
                ctx.fillStyle = Theme.graphNodeTag
            }
            ctx.fill()
            ctx.strokeStyle = Theme.bg
            ctx.lineWidth = 1.5
            ctx.stroke()
            ctx.fillStyle = Theme.graphLabel
            ctx.font = (9 / zoom) + "px sans-serif"
            const txt = nd.name.length > 14 ? nd.name.substring(0, 13) + "…" : nd.name
            ctx.fillText(txt, p.x, p.y + r + 10 / zoom)
        }

        ctx.restore()
    }

    onPaint: paintCanvas()

    MouseArea {
        anchors.fill: parent
        acceptedButtons: Qt.LeftButton
        hoverEnabled: true
        cursorShape: g.dragKey.length > 0 ? Qt.ClosedHandCursor : Qt.ArrowCursor
        onWheel: (w) => {
            const factor = w.angleDelta.y > 0 ? 1.15 : 0.87
            g.zoom = Math.max(0.2, Math.min(5.0, g.zoom * factor))
            g.requestPaint()
        }
        onPressed: (m) => {
            g.dragKey = ""
            g.lastMouseX = m.x
            g.lastMouseY = m.y
            const gx = (m.x - width / 2 - panX) / zoom + width / 2
            const gy = (m.y - height / 2 - panY) / zoom + height / 2
            for (const key in g.pos) {
                const p = g.pos[key]
                const dx = gx - p.x, dy = gy - p.y
                if (dx * dx + dy * dy <= 256) { g.dragKey = key; break }
            }
        }
        onPositionChanged: (m) => {
            if (!pressed) return
            if (g.dragKey.length > 0 && g.pos[g.dragKey]) {
                const gx = (m.x - width / 2 - panX) / zoom + width / 2
                const gy = (m.y - height / 2 - panY) / zoom + height / 2
                g.pos[g.dragKey] = { x: gx, y: gy }
            } else if (pressed) {
                g.panX += m.x - g.lastMouseX
                g.panY += m.y - g.lastMouseY
            }
            g.lastMouseX = m.x
            g.lastMouseY = m.y
            g.requestPaint()
        }
        onReleased: (m) => {
            const wasDrag = g.dragKey.length > 0
            const gx = (m.x - width / 2 - panX) / zoom + width / 2
            const gy = (m.y - height / 2 - panY) / zoom + height / 2
            if (!wasDrag) {
                for (const key in g.pos) {
                    const p = g.pos[key]
                    const dx = gx - p.x, dy = gy - p.y
                    if (dx * dx + dy * dy <= 144) {
                        const nd = g.nodeForKey(key)
                        if (nd && nd.type === "file") g.fileClicked(nd.key)
                        break
                    }
                }
            }
            g.dragKey = ""
            g.requestPaint()
        }
        onDoubleClicked: { g.zoom = 1.0; g.panX = 0; g.panY = 0; g.relayout() }
    }
}