import { walk } from 'estree-walker'
import recast from 'recast'

//my thoughts on this code are: na na na nani the fuck
export default function preprocess(opts) {
	return {
		name: "preprocess",
		transform: {
			order: 'pre',
			handler(code) {
				const state = {
					failedIf: false
				}
				const parse = this.parse 

				const comments = []
				const ast = recast.parse(code, {
					parser: this
				})
				walk(ast, { //WALK CST FOR COMPTIME_VARS
					enter(node, parent, prop, index) {
						if (parent?.type === "MemberExpression" && parent?.property === node) {
							if (state.failedIf) {
								delete parent[prop]
							}
							return //ignore childs of objects ie console.log
						} else if (node.type === "Identifier") {
							if (opts.values) {
								for (const i in opts.values) {
									if (i === node.name) {
										console.log(`Found comp-time var ${i} with value ${opts.values[i]}`)
										const res = eval(`(${opts.values[i]})`)
										if (typeof res === "string") {
											parent[prop] = [ parse(`('${res}')`).body[0].expression ]
										} else {
											parent[prop] = [ parse(`(${res})`).body[0].expression ]
										}
										return
									}
								}
							}
						} else if (node.comments) {
							node.comments.forEach((cmt, cidx) => {
								for (const i in opts.transforms) {
									if (cmt.value.startsWith(i)) {
										console.log(`Found comp-time comment transformation ${i}`)
										opts.transforms[i](cmt, node, cidx)
										return
									}
								}
								if (cmt.value.toUpperCase().startsWith("#IF ")) {
									const vari = cmt.value.substring(4)
									node.comments = []
									if (opts.values[vari] === undefined) {
										throw new Error("Cannot use undefined comp-time variable in #IF macro!")
									} else {
										const res = eval(`(${opts.values[vari]})`)
										if (!!res) {
											console.log("Broke into #IF macro")
										} else {
											console.log(`Unmet #IF for ${vari}`)
											state.failedIf = true
										}
									}
								} else if (cmt.value.toUpperCase().startsWith("#IFNOT ")) {
									const vari = cmt.value.substring(7)
									node.comments = []
									if (opts.values[vari] === undefined) {
										throw new Error("Cannot use undefined comp-time variable in #IFNOT macro!")
									} else {
										const res = eval(`(${opts.values[vari]})`)
										if (!res) {
											console.log("Broke into #IFNOT macro")
										} else {
											console.log(`Unmet #IFNOT for ${vari} at Line ${cmt.loc.start.line}:${cmt.loc.start.column}`)
											state.failedIf = true
										}
									}
								} else if (cmt.value.toUpperCase().startsWith("#END")) {
									console.log("Broke out of macro")
									node.comments = []
									state.failedIf = false
								}
							})
						} else {
							if (state.failedIf) {
								delete parent[prop]
							}
						}
					}
				})
				return { code: recast.print(ast).code }
			}
		}
	}
}