import type {
    AcceptanceCriteriaItemModel,
    AcceptanceCriteriaModel,
} from '@/types/models/acceptance-criteria-model';

const MAX_INDENT_LEVEL = 8;

export type AcceptanceCriteriaEditorState = {
    checklist: string;
    summary: string;
};

export const emptyAcceptanceCriteria = (): AcceptanceCriteriaModel => ({
    summary: null,
    items: [],
});

export const normalizeAcceptanceCriteria = (
    value: AcceptanceCriteriaModel | null | undefined,
): AcceptanceCriteriaModel => {
    if (value === null || value === undefined) {
        return emptyAcceptanceCriteria();
    }

    const summary = value.summary?.trim() ?? null;
    const items = Array.isArray(value.items)
        ? value.items
              .map((item) => ({
                  checked: item.checked === true,
                  indent: clampIndent(item.indent),
                  text: item.text.trim(),
              }))
              .filter((item) => item.text !== '')
        : [];

    return {
        summary: summary === '' ? null : summary,
        items,
    };
};

export const parseChecklistLines = (
    checklistInput: string,
): AcceptanceCriteriaItemModel[] => {
    if (checklistInput.trim() === '') {
        return [];
    }

    return checklistInput
        .split(/\r?\n/u)
        .map((line) => parseChecklistLine(line))
        .filter(
            (parsedLine): parsedLine is AcceptanceCriteriaItemModel =>
                parsedLine !== null,
        );
};

export const formatChecklistLines = (
    items: AcceptanceCriteriaItemModel[],
): string => {
    return items
        .map((item) => {
            const indentation = '  '.repeat(clampIndent(item.indent));
            const marker = item.checked ? '[x]' : '[ ]';

            return `${indentation}${marker} ${item.text}`;
        })
        .join('\n');
};

export const buildAcceptanceCriteria = (
    summaryInput: string,
    checklistInput: string,
): AcceptanceCriteriaModel => {
    const summary = summaryInput.trim();

    return normalizeAcceptanceCriteria({
        summary: summary === '' ? null : summary,
        items: parseChecklistLines(checklistInput),
    });
};

export const acceptanceCriteriaToEditorState = (
    value: AcceptanceCriteriaModel | null | undefined,
): AcceptanceCriteriaEditorState => {
    const normalized = normalizeAcceptanceCriteria(value);

    return {
        checklist: formatChecklistLines(normalized.items),
        summary: normalized.summary ?? '',
    };
};

const parseChecklistLine = (
    line: string,
): AcceptanceCriteriaItemModel | null => {
    const normalizedLine = line.replaceAll('\t', '  ').trimEnd();

    if (normalizedLine.trim() === '') {
        return null;
    }

    const match = /^(?<indent>\s*)(?<content>.+)$/u.exec(normalizedLine);

    if (match === null || match.groups === undefined) {
        return null;
    }

    const indentLevel = clampIndent(
        Math.floor(match.groups.indent.length / 2),
    );
    let content = match.groups.content.trim();
    let checked = false;

    const checkboxMatch =
        /^(?:[-*+]\s+)?\[(?<state>[xX ])\]\s*(?<text>.+)$/u.exec(content);

    if (checkboxMatch?.groups !== undefined) {
        checked = checkboxMatch.groups.state.toLowerCase() === 'x';
        content = checkboxMatch.groups.text.trim();
    } else {
        const bulletMatch = /^[-*+]\s+(?<text>.+)$/u.exec(content);

        if (bulletMatch?.groups !== undefined) {
            content = bulletMatch.groups.text.trim();
        }
    }

    if (content === '') {
        return null;
    }

    return {
        checked,
        indent: indentLevel,
        text: content,
    };
};

const clampIndent = (indent: number): number => {
    if (!Number.isFinite(indent)) {
        return 0;
    }

    return Math.max(0, Math.min(MAX_INDENT_LEVEL, Math.trunc(indent)));
};