export const cursors = []

export class Cursor {
    constructor(targetNode = null, insertIndex = null) {
        this.targetNode = targetNode // 初始时可以直接指定目标文本节点
        this.insertIndex = insertIndex // 初始时可以直接指定插入位置索引
        this.range = document.createRange()
        this.cursorElement = this.createCursorElement()
        document.body.appendChild(this.cursorElement)
    }

    // 创建光标元素
    createCursorElement() {
        const cursorElement = document.createElement("div")
        Object.assign(cursorElement.style, {
            position: "absolute",
            width: "2px",
            height: "1em",
            backgroundColor: "black",
            zIndex: "9999",
            pointerEvents: "none",
            display: "none", // 初始隐藏
            transition: "all 0.1s ease"
        })
        return cursorElement
    }

    // 设置目标文本节点和插入位置
    setTarget(node, index) {
        this.targetNode = node
        this.insertIndex = index
        this.updateRange()
    }

    // 更新范围
    updateRange() {
        if (this.targetNode && this.insertIndex !== null) {
            this.range.setStart(this.targetNode, this.insertIndex)
            this.range.setEnd(this.targetNode, this.insertIndex)
        }
    }

    // 插入文本
    insertText(text) {
        const insertionNode = document.createTextNode(text)
        this.updateRange()
        this.range.insertNode(insertionNode)
        // 更新插入位置
        this.insertIndex += text.length
        this.updateRange()  // 更新光标范围
        return insertionNode
    }

    // 获取当前光标的矩形位置
    getBoundingClientRect() {
        this.updateRange()
        return this.range.getBoundingClientRect()
    }

    // 更新光标位置
    updatePosition(rect) {
        if (!rect) {
            this.hide()
            return
        }
        this.cursorElement.style.left = `${rect.left}px`
        this.cursorElement.style.top = `${rect.top}px`
        this.cursorElement.style.display = "block"
    }

    // 隐藏光标
    hide() {
        this.cursorElement.style.display = "none"
    }

    // 移除光标元素
    remove() {
        this.cursorElement.remove()
    }

    move(key) {
        // 获取目标节点的上下兄弟节点（li元素)
        const children = Array.from(this.targetNode.parentNode.parentNode.children)
        const siblings = children.filter(node => {
            return node !== this.targetNode && node.nodeType === Node.ELEMENT_NODE
        }).map(item => {
            return Array.from(item.childNodes).find(node => node.nodeType === Node.TEXT_NODE)
        })
        const currentIndex = siblings.indexOf(this.targetNode)

        if (key === "ArrowUp" && currentIndex > 0) {
            const prevSibling = siblings[currentIndex - 1]
            const index = Math.max(0, Math.min(prevSibling.textContent.length, this.insertIndex))
            this.setTarget(prevSibling, index)  // 光标在上一个兄弟元素的起始位置
            return
        }

        if (key === "ArrowDown" && currentIndex >= 0 && currentIndex < siblings.length - 1) {
            const nextSibling = siblings[currentIndex + 1]
            const index = Math.max(0, Math.min(nextSibling.textContent.length, this.insertIndex))
            this.setTarget(nextSibling, index)  // 光标在下一个兄弟元素的起始位置
            return
        }

        if (key === "ArrowLeft" && this.insertIndex > 0) {
            this.insertIndex = Math.max(0, Math.min(this.targetNode.textContent.length, this.insertIndex - 1))
            this.updateRange()
            return
        }

        if (key === "ArrowRight" && this.insertIndex < this.targetNode.textContent.length) {
            this.insertIndex = Math.max(0, Math.min(this.targetNode.textContent.length, this.insertIndex + 1))
            this.updateRange()
            return
        }
    }
}

export default { cursors, Cursor }