"""
Citation formatters: Vancouver, APA 7th edition, and AMA style.
Vancouver is the standard for UK nursing and medical publications.
APA 7th is used by some UK university nursing programmes.
"""


# ---------------------------------------------------------------------------
# APA 7th Edition
# ---------------------------------------------------------------------------

def format_apa7(article: dict) -> str:
    """
    APA 7th edition journal article format:
    Author, F. M., & Author, F. M. (Year). Title of article.
    *Journal Name*, *Volume*(Issue), Pages. https://doi.org/xxxxx
    """
    authors_str = _apa_authors(article.get("authors", []))
    year    = article.get("year") or "n.d."
    title   = _clean_title(article.get("title", ""))
    journal = article.get("journal", "")
    volume  = article.get("volume", "")
    issue   = article.get("issue", "")
    pages   = article.get("pages", "")
    doi     = _clean_doi(article.get("doi", ""))
    url     = article.get("url", "")

    citation = f"{authors_str} ({year}). {title}."

    if journal:
        citation += f" *{journal}*"
        if volume:
            citation += f", *{volume}*"
            if issue:
                citation += f"({issue})"
        if pages:
            citation += f", {pages}"
        citation += "."

    if doi:
        citation += f" https://doi.org/{doi}"
    elif url:
        citation += f" {url}"

    return citation


def _apa_authors(authors: list[str]) -> str:
    if not authors:
        return "Unknown Author"

    formatted = [_apa_single(a) for a in authors[:20]]

    # APA 7: 21+ authors → first 19, ellipsis, last author
    if len(authors) > 20:
        last = _apa_single(authors[-1])
        return ", ".join(formatted[:19]) + ", . . . " + last

    if len(formatted) == 1:
        return formatted[0]
    if len(formatted) == 2:
        return f"{formatted[0]}, & {formatted[1]}"
    return ", ".join(formatted[:-1]) + f", & {formatted[-1]}"


def _apa_single(name: str) -> str:
    name = name.strip()
    if name.lower() in ("et al.", "et al"):
        return "et al."
    if "," in name:
        # "Last, First M." → keep as-is, just ensure initials
        last, *rest = name.split(",", 1)
        initials = _initials(" ".join(rest))
        return f"{last.strip()}, {initials}"
    parts = name.split()
    if len(parts) >= 2:
        # Detect PubMed/Europe PMC "Surname JK" format
        if _is_initials_token(parts[-1]):
            last = " ".join(parts[:-1])   # handles "van der Berg JK"
            initials = _initials_from_str(parts[-1])
            return f"{last}, {initials}"
        last = parts[-1]
        initials = _initials(" ".join(parts[:-1]))
        return f"{last}, {initials}"
    return name


# ---------------------------------------------------------------------------
# Vancouver Style (UK nursing / medical standard)
# ---------------------------------------------------------------------------

def format_vancouver(article: dict) -> str:
    """
    Vancouver citation format — standard for UK nursing and medical journals
    (Nursing Standard, BJN, JAN, BMJ, Lancet, NEJM etc.)

    Format: Surname Initial(s), Surname Initial(s). Title. Journal Abbrev.
            Year;Volume(Issue):Pages. doi:xxxxx
    Up to 6 authors; if more, list first 6 then 'et al.'
    """
    authors_str = _vancouver_authors(article.get("authors", []))
    year    = article.get("year", "")
    title   = _clean_title(article.get("title", ""))
    journal = article.get("journal", "")
    volume  = article.get("volume", "")
    issue   = article.get("issue", "")
    pages   = article.get("pages", "")
    doi     = _clean_doi(article.get("doi", ""))
    url     = article.get("url", "")

    # Vancouver: no period after title if journal follows immediately
    citation = f"{authors_str}. {title}."

    if journal:
        citation += f" {journal}."

    if year:
        citation += f" {year}"
        if volume:
            citation += f";{volume}"
            if issue:
                citation += f"({issue})"
        if pages:
            citation += f":{pages}"
        citation += "."

    if doi:
        citation += f" doi:{doi}"
    elif url:
        citation += f" Available from: {url}"

    return citation


def _vancouver_authors(authors: list[str]) -> str:
    if not authors:
        return "Unknown Author"
    formatted = [_vancouver_single(a) for a in authors[:6]]
    if len(authors) > 6:
        formatted.append("et al")
    return ", ".join(formatted)


def _vancouver_single(name: str) -> str:
    """Convert name to Vancouver format: Surname AB"""
    name = name.strip()
    if name.lower() in ("et al.", "et al"):
        return "et al"
    if "," in name:
        last, *rest = name.split(",", 1)
        initials = "".join(p[0].upper() for p in " ".join(rest).split() if p)
        return f"{last.strip()} {initials}"
    parts = name.split()
    if len(parts) >= 2:
        # Detect PubMed/Europe PMC "Surname JK" format
        if _is_initials_token(parts[-1]):
            last = " ".join(parts[:-1])
            initials = parts[-1].upper()   # already run-together: "JK" stays "JK"
            return f"{last} {initials}"
        last = parts[-1]
        initials = "".join(p[0].upper() for p in parts[:-1] if p)
        return f"{last} {initials}"
    return name


# ---------------------------------------------------------------------------
# Harvard Style (Cite Them Right — common UK university nursing standard)
# ---------------------------------------------------------------------------

def format_harvard(article: dict) -> str:
    """
    Harvard citation format (Cite Them Right 12th ed.) — used by many UK
    universities for nursing essays where Vancouver is not mandated.

    Format: Surname, Initial(s). and Surname, Initial(s). (Year) 'Title of
            article', *Journal Name*, Volume(Issue), pp. Pages.
    Up to 3 authors listed; 4+ → first author et al.
    """
    authors_str = _harvard_authors(article.get("authors", []))
    year    = article.get("year") or "n.d."
    title   = _clean_title(article.get("title", ""))
    journal = article.get("journal", "")
    volume  = article.get("volume", "")
    issue   = article.get("issue", "")
    pages   = article.get("pages", "")
    doi     = _clean_doi(article.get("doi", ""))
    url     = article.get("url", "")

    citation = f"{authors_str} ({year}) '{title}',"

    if journal:
        citation += f" *{journal}*,"
        if volume:
            citation += f" {volume}"
            if issue:
                citation += f"({issue})"
            citation += ","
        if pages:
            citation += f" pp. {pages}."
        else:
            citation = citation.rstrip(",") + "."
    else:
        citation = citation.rstrip(",") + "."

    if doi:
        citation += f" doi:{doi}"
    elif url:
        citation += f" Available at: {url} (Accessed: {_access_year(year)})"

    return citation


def _harvard_authors(authors: list[str]) -> str:
    if not authors:
        return "Anon."
    if len(authors) > 3:
        return _harvard_single(authors[0]) + " et al."
    formatted = [_harvard_single(a) for a in authors]
    if len(formatted) == 1:
        return formatted[0]
    return ", ".join(formatted[:-1]) + " and " + formatted[-1]


def _harvard_single(name: str) -> str:
    """Convert to Harvard format: Surname, A.B."""
    name = name.strip()
    if name.lower() in ("et al.", "et al"):
        return "et al."
    if "," in name:
        last, *rest = name.split(",", 1)
        initials = _initials(" ".join(rest))
        return f"{last.strip()}, {initials}"
    parts = name.split()
    if len(parts) >= 2:
        # Detect PubMed/Europe PMC "Surname JK" format (e.g. "Smith JK")
        # Without this check, "Smith JK" → last="JK", initials="S." → "JK, S." (wrong)
        if _is_initials_token(parts[-1]):
            last = " ".join(parts[:-1])   # handles multi-word surnames too
            initials = _initials_from_str(parts[-1])   # "JK" → "J. K."
            return f"{last}, {initials}"
        last = parts[-1]
        initials = _initials(" ".join(parts[:-1]))
        return f"{last}, {initials}"
    return name


def _access_year(year: str) -> str:
    """Return a sensible access date placeholder."""
    return "date accessed"


# ---------------------------------------------------------------------------
# AMA Style
# ---------------------------------------------------------------------------

def format_ama(article: dict) -> str:
    """
    AMA citation format (used in some nursing / medical journals):
    Last FM, Last FM. Title. Journal. Year;Vol(Issue):Pages. doi:xxxxx
    """
    authors_str = _ama_authors(article.get("authors", []))
    year    = article.get("year", "")
    title   = _clean_title(article.get("title", ""))
    journal = article.get("journal", "")
    volume  = article.get("volume", "")
    issue   = article.get("issue", "")
    pages   = article.get("pages", "")
    doi     = _clean_doi(article.get("doi", ""))

    citation = f"{authors_str}. {title}. *{journal}*."

    if year:
        citation += f" {year}"
    if volume:
        citation += f";{volume}"
        if issue:
            citation += f"({issue})"
    if pages:
        citation += f":{pages}"
    citation += "."

    if doi:
        citation += f" doi:{doi}"

    return citation


def _ama_authors(authors: list[str]) -> str:
    if not authors:
        return "Unknown Author"

    formatted = [_ama_single(a) for a in authors[:6]]
    if len(authors) > 6:
        formatted.append("et al")

    return ", ".join(formatted)


def _ama_single(name: str) -> str:
    name = name.strip()
    if name.lower() in ("et al.", "et al", "et al."):
        return "et al"
    if "," in name:
        last, *rest = name.split(",", 1)
        initials = "".join(p[0].upper() for p in " ".join(rest).split() if p)
        return f"{last.strip()} {initials}"
    parts = name.split()
    if len(parts) >= 2:
        # Detect PubMed/Europe PMC "Surname JK" format
        if _is_initials_token(parts[-1]):
            last = " ".join(parts[:-1])
            initials = parts[-1].upper()   # AMA uses run-together: "Smith JK"
            return f"{last} {initials}"
        last = parts[-1]
        initials = "".join(p[0].upper() for p in parts[:-1] if p)
        return f"{last} {initials}"
    return name


# ---------------------------------------------------------------------------
# Shared helpers
# ---------------------------------------------------------------------------

def _initials(first_middle: str) -> str:
    """Convert first/middle name string to initials: "John Paul" → "J. P." """
    parts = first_middle.strip().split()
    return " ".join(p[0].upper() + "." for p in parts if p)


def _initials_from_str(token: str) -> str:
    """
    Expand a run-together initials token from PubMed/Europe PMC into dotted
    initials: "JK" → "J. K."  |  "AB" → "A. B."  |  "J" → "J."
    """
    return " ".join(c.upper() + "." for c in token if c.isalpha())


def _is_initials_token(token: str) -> bool:
    """
    Return True when a name token looks like run-together initials rather than
    a proper word — i.e. it is 1–4 uppercase letters with no vowels OR is
    entirely uppercase and short.

    Examples that return True : "JK", "AB", "J", "JKL", "ABCD"
    Examples that return False: "Smith", "John", "van", "De", "O'Brien"
    """
    if not token or not token.isalpha():
        return False
    if len(token) > 4:
        return False
    # Single letter is always an initial
    if len(token) == 1:
        return token.isupper()
    # Multi-char: must be all-uppercase (PubMed stores "Smith JK", not "Smith jk")
    return token.isupper()


def _clean_title(title: str) -> str:
    return title.strip().rstrip(".")


def _clean_doi(doi: str) -> str:
    doi = doi.strip()
    for prefix in ("https://doi.org/", "http://doi.org/", "doi:", "doi: "):
        if doi.lower().startswith(prefix):
            doi = doi[len(prefix):]
    return doi