import { capitalise, escapePronunciationString } from '#shared/helpers.ts';
import type { MorphemeValues } from '#shared/language/morphemes.ts';
import type { NounConvention, NounDeclension, Numerus } from '#shared/nouns.ts';
import type { Config } from '~~/locale/config.ts';

export type ExamplePart = string | ExamplePartMorpheme | ExamplePartNoun;

interface ExamplePartMorpheme {
    type: 'morpheme';
    morpheme: string;
    capitalise?: boolean;
}

interface ExamplePartNoun {
    type: 'noun';
    stems: Record<string, string>;
    nounClass: string;
    caseAbbreviation: string;
    numerus?: Numerus;
}

export interface ExampleValues {
    morphemeValues: MorphemeValues;
    plural?: boolean;
    nounConvention?: NounConvention;
    nounDeclensions?: Record<string, NounDeclension>;
}

const placeholderRegex = /{([^}]+)}/g;
const morphemeRegex = /^(?<capitalise>'?)(?<morpheme>[a-z0-9_]+)$/;
const nounRegex = /^:noun (?<stems>\S+) (?<nounClass>\S+) (?<caseAbbreviation>\w+) (?<numerus>singular|plural)$/;

export class Example {
    parts: ExamplePart[];

    constructor(parts: ExamplePart[]) {
        this.parts = parts;
    }

    static parse(example: string): Example {
        const parts: ExamplePart[] = [];
        let lastPosition = 0;

        const processStaticText = (match: RegExpExecArray) => {
            const textBefore = example.substring(lastPosition, match.index);
            if (textBefore) {
                parts.push(textBefore);
            }
            lastPosition = match.index + match[0].length;
        };

        for (const match of example.matchAll(placeholderRegex)) {
            const morphemeMatch = match[1].match(morphemeRegex);
            if (morphemeMatch && morphemeMatch.groups) {
                processStaticText(match);
                parts.push({
                    type: 'morpheme',
                    capitalise: !!morphemeMatch.groups.capitalise,
                    morpheme: morphemeMatch.groups.morpheme,
                });
                continue;
            }
            const nounMatch = match[1].match(nounRegex);
            if (nounMatch && nounMatch.groups) {
                processStaticText(match);
                parts.push({
                    type: 'noun',
                    stems: Object.fromEntries(nounMatch.groups.stems.split('|').map((stem) => {
                        const chunks = stem.split(':');
                        return chunks.length === 1 ? ['default', chunks[0]] : chunks;
                    })),
                    nounClass: nounMatch.groups.nounClass,
                    caseAbbreviation: nounMatch.groups.caseAbbreviation,
                    numerus: nounMatch.groups.numerus as Numerus | undefined,
                });
            }
        }

        const textAfter = example.substring(lastPosition);
        if (textAfter.length) {
            parts.push(textAfter);
        }

        return new Example(parts);
    }

    hasMorpheme(morpheme: string): boolean {
        return this.parts.filter((part) => typeof part !== 'string' && part.type === 'morpheme')
            .some((part) => part.morpheme === morpheme);
    }

    areRequiredExampleValuesPresent(exampleValues: ExampleValues): boolean {
        return this.parts.every((part, index) => this.getSpelling(index, exampleValues) !== undefined);
    }

    getSpelling(index: number, exampleValues: ExampleValues): string | undefined {
        const part = this.parts[index];

        if (typeof part === 'string') {
            return part;
        }
        switch (part.type) {
            case 'morpheme': {
                const spelling = exampleValues.morphemeValues.getSpelling(part.morpheme);
                return spelling !== undefined && part.capitalise ? capitalise(spelling) : spelling;
            }
            case 'noun': {
                if (exampleValues.nounConvention === undefined || exampleValues.nounDeclensions === undefined) {
                    return undefined;
                }
                const template = exampleValues.nounConvention.templates[part.nounClass];
                if (template === undefined) {
                    return undefined;
                }
                const stem = part.stems[template.stem ?? 'default'];
                const numerus = part.numerus ?? 'singular';
                const declension = exampleValues.nounDeclensions[template.declension][numerus];
                if (declension === undefined) {
                    return undefined;
                }
                const declensionSuffix = declension[part.caseAbbreviation];
                return `${stem}${template.suffix}${declensionSuffix}`;
            }
        }
    }

    toSpellingString(exampleValues: ExampleValues): string {
        return this.parts.map((part, index) => this.getSpelling(index, exampleValues)).join('');
    }

    toPronunciationString(
        config: Config,
        exampleValues: ExampleValues,
    ): string | undefined {
        const buildPronunciation = (morpheme: string): string | false | undefined => {
            const pronunciation = exampleValues.morphemeValues.getPronunciation(morpheme);
            if (pronunciation === false) {
                return false;
            }
            if (pronunciation !== undefined) {
                return pronunciation.startsWith('=') ? pronunciation.substring(1) : `/${pronunciation}/`;
            }

            const spelling = exampleValues.morphemeValues.getSpelling(morpheme);
            if (config.pronunciation?.ipa && spelling) {
                return spelling.split('').map((c) => [' ', ',', '.', ':', ';', '–', '-'].includes(c) ? c : `/${c}/`)
                    .join('');
            }

            return spelling;
        };

        const pronunciationParts = this.parts.map((part, index) => {
            if (typeof part === 'string') {
                return escapePronunciationString(part);
            }
            switch (part.type) {
                case 'morpheme':
                    return buildPronunciation(part.morpheme);
                case 'noun':
                    return this.getSpelling(index, exampleValues);
            }
        });

        if (pronunciationParts.some((part) => part === false)) {
            return undefined;
        }
        return pronunciationParts.join('');
    }
}