import type { CachedDocumentation, CachedDocumentationEntry } from './documentation.js'

type MaybeOverwrite =
  | string
  | {
      text: string
      overwrite: boolean
  }

interface RegexRule {
    _cached?: RegExp

    regex: string
    flags?: string
    repl: string
}

interface DescriptionsYaml {
    objects: Record<
        string,
        {
            desc?: MaybeOverwrite
            arguments?: Record<string, MaybeOverwrite>
        }
    >

    arguments: Record<string, string>

    regex: RegexRule[]
}

function unwrapMaybe(what: MaybeOverwrite, has: boolean): string | undefined {
    let text: string
    let overwrite = false

    if (typeof what === 'object') {
        if (!what.text) throw new Error('Invalid overwrite object')
        text = what.text
        overwrite = what.overwrite
    } else {
        text = what
    }

    if (!has || overwrite) {
        return text
    }

    return undefined
}

export function applyDescriptionsYamlFile(input: CachedDocumentation, yaml: unknown): CachedDocumentation {
    const { objects: byObjects, arguments: byArguments, regex: byRegex } = yaml as DescriptionsYaml

    // first create an index of all classes and methods
    const objIndex: Record<string, CachedDocumentationEntry> = {}

    function indexObject(obj: Record<string, CachedDocumentationEntry>, prefix: string) {
        for (const name in obj) {
            objIndex[prefix + name] = obj[name]!
        }
    }

    indexObject(input.classes, 'c_')
    indexObject(input.methods, 'm_')

    // process byObjects
    for (const name in byObjects) {
        const rules = byObjects[name]
        const obj = objIndex[name]

        if (!obj) continue

        if (rules.desc) {
            const desc = unwrapMaybe(rules.desc, Boolean(obj.comment))
            if (desc) obj.comment = desc
        }

        if (rules.arguments) {
            for (const arg in rules.arguments) {
                const repl = unwrapMaybe(rules.arguments[arg], obj.arguments !== undefined && arg in obj.arguments)

                if (repl) {
                    if (!obj.arguments) obj.arguments = {}
                    obj.arguments[arg] = repl
                }
            }
        }
    }

    // process byArguments
    for (const i in objIndex) {
        const obj = objIndex[i]

        for (const arg in byArguments) {
            if (obj.arguments && !(arg in obj.arguments)) continue

            const repl = unwrapMaybe(byArguments[arg], Boolean(obj.arguments && arg in obj.arguments))

            if (repl) {
                if (!obj.arguments) obj.arguments = {}
                obj.arguments[arg] = repl
            }
        }
    }

    // process byRegex
    function applyRegex(str: string | undefined, rule: RegexRule) {
        if (!str) return ''

        if (!rule._cached) {
            let flags = rule.flags || ''
            if (!flags.includes('g')) flags += 'g'

            rule._cached = new RegExp(rule.regex, flags)
        }

        return str.replace(rule._cached, rule.repl)
    }

    for (const i in objIndex) {
        const obj = objIndex[i]

        byRegex.forEach((rule) => {
            obj.comment = applyRegex(obj.comment, rule)

            if (obj.arguments) {
                for (const name in obj.arguments) {
                    obj.arguments[name] = applyRegex(obj.arguments[name], rule)
                }
            }
        })
    }

    for (const i in input.unions) {
        byRegex.forEach((rule) => {
            input.unions[i] = applyRegex(input.unions[i], rule)
        })
    }

    return input
}