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.range.setStart(this.targetNode, this.insertIndex)
        this.range.setEnd(this.targetNode, this.insertIndex)
        return this.range.getBoundingClientRect()
    }

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

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

    oninput({ value }) {
        const text = this.targetNode.textContent
        const left = text.slice(0, this.insertIndex)
        const right = text.slice(this.insertIndex)
        this.insertIndex += value.length
        this.targetNode.textContent = left + value + right
        this.updatePosition(this.getBoundingClientRect())
    }

    onkeydown({ key }) {
        if (key === "ArrowUp" && this.targetNode.parentNode.previousElementSibling) {
            // 先取兄弟元素的最后一个子元素, 没有则取兄弟元素, 没有则向上回溯
            this.targetNode = Array.from(this.targetNode.parentNode.previousElementSibling.childNodes).find(node => node.nodeType === Node.TEXT_NODE)
            this.insertIndex = Math.max(0, Math.min(this.targetNode.textContent.length, this.insertIndex))
            this.updatePosition(this.getBoundingClientRect())
        }
        if (key === "ArrowDown" && this.targetNode.parentNode.nextElementSibling) {
            // 先取当前子元素, 没有则取下一个兄弟元素, 没有则向上回溯
            this.targetNode = Array.from(this.targetNode.parentNode.nextElementSibling.childNodes).find(node => node.nodeType === Node.TEXT_NODE)
            this.insertIndex = Math.max(0, Math.min(this.targetNode.textContent.length, this.insertIndex))
            this.updatePosition(this.getBoundingClientRect())
        }
        if (key === "ArrowLeft") {
            this.insertIndex = Math.max(0, Math.min(this.targetNode.textContent.length, this.insertIndex - 1))
            return this.updatePosition(this.getBoundingClientRect())
        }
        if (key === "ArrowRight") {
            this.insertIndex = Math.max(0, Math.min(this.targetNode.textContent.length, this.insertIndex + 1))
            return this.updatePosition(this.getBoundingClientRect())
        }
        if (key === "Backspace") {
            const text = this.targetNode.textContent
            const left = text.slice(0, Math.max(0, this.insertIndex - 1))
            const right = text.slice(this.insertIndex)
            this.targetNode.textContent = left + right
            this.insertIndex = Math.max(0, this.insertIndex - 1)
            return this.updatePosition(this.getBoundingClientRect())
        }
    }
}

export default { cursors, Cursor }