"""
Primitive registry and built-in pure functions.

All primitives here are pure (no I/O).  Async / I/O primitives live in
separate modules and are registered at app startup.
"""

from __future__ import annotations

import math
from typing import Any, Callable

from .types import Keyword, Lambda, NIL


# ---------------------------------------------------------------------------
# Registry
# ---------------------------------------------------------------------------

_PRIMITIVES: dict[str, Callable] = {}


def register_primitive(name: str):
    """Decorator that registers a callable as a named primitive.

    Usage::

        @register_primitive("str")
        def prim_str(*args):
            return "".join(str(a) for a in args)
    """
    def decorator(fn: Callable) -> Callable:
        _PRIMITIVES[name] = fn
        return fn
    return decorator


def get_primitive(name: str) -> Callable | None:
    return _PRIMITIVES.get(name)


def all_primitives() -> dict[str, Callable]:
    """Return a snapshot of the registry (name → callable)."""
    return dict(_PRIMITIVES)


# ---------------------------------------------------------------------------
# Arithmetic
# ---------------------------------------------------------------------------

@register_primitive("+")
def prim_add(*args: Any) -> Any:
    return sum(args)

@register_primitive("-")
def prim_sub(a: Any, b: Any = None) -> Any:
    return -a if b is None else a - b

@register_primitive("*")
def prim_mul(*args: Any) -> Any:
    r = 1
    for a in args:
        r *= a
    return r

@register_primitive("/")
def prim_div(a: Any, b: Any) -> Any:
    return a / b

@register_primitive("mod")
def prim_mod(a: Any, b: Any) -> Any:
    return a % b

@register_primitive("sqrt")
def prim_sqrt(x: Any) -> float:
    return math.sqrt(x)

@register_primitive("pow")
def prim_pow(x: Any, n: Any) -> Any:
    return x ** n

@register_primitive("abs")
def prim_abs(x: Any) -> Any:
    return abs(x)

@register_primitive("floor")
def prim_floor(x: Any) -> int:
    return math.floor(x)

@register_primitive("ceil")
def prim_ceil(x: Any) -> int:
    return math.ceil(x)

@register_primitive("round")
def prim_round(x: Any, ndigits: Any = 0) -> Any:
    return round(x, int(ndigits))

@register_primitive("min")
def prim_min(*args: Any) -> Any:
    if len(args) == 1 and isinstance(args[0], (list, tuple)):
        return min(args[0])
    return min(args)

@register_primitive("max")
def prim_max(*args: Any) -> Any:
    if len(args) == 1 and isinstance(args[0], (list, tuple)):
        return max(args[0])
    return max(args)

@register_primitive("clamp")
def prim_clamp(x: Any, lo: Any, hi: Any) -> Any:
    return max(lo, min(hi, x))

@register_primitive("inc")
def prim_inc(n: Any) -> Any:
    return n + 1

@register_primitive("dec")
def prim_dec(n: Any) -> Any:
    return n - 1


# ---------------------------------------------------------------------------
# Comparison
# ---------------------------------------------------------------------------

@register_primitive("=")
def prim_eq(a: Any, b: Any) -> bool:
    return a == b

@register_primitive("!=")
def prim_neq(a: Any, b: Any) -> bool:
    return a != b

@register_primitive("<")
def prim_lt(a: Any, b: Any) -> bool:
    return a < b

@register_primitive(">")
def prim_gt(a: Any, b: Any) -> bool:
    return a > b

@register_primitive("<=")
def prim_lte(a: Any, b: Any) -> bool:
    return a <= b

@register_primitive(">=")
def prim_gte(a: Any, b: Any) -> bool:
    return a >= b


# ---------------------------------------------------------------------------
# Predicates
# ---------------------------------------------------------------------------

@register_primitive("odd?")
def prim_is_odd(n: Any) -> bool:
    return n % 2 == 1

@register_primitive("even?")
def prim_is_even(n: Any) -> bool:
    return n % 2 == 0

@register_primitive("zero?")
def prim_is_zero(n: Any) -> bool:
    return n == 0

@register_primitive("nil?")
def prim_is_nil(x: Any) -> bool:
    return x is None or x is NIL

@register_primitive("number?")
def prim_is_number(x: Any) -> bool:
    return isinstance(x, (int, float))

@register_primitive("string?")
def prim_is_string(x: Any) -> bool:
    return isinstance(x, str)

@register_primitive("list?")
def prim_is_list(x: Any) -> bool:
    return isinstance(x, list)

@register_primitive("dict?")
def prim_is_dict(x: Any) -> bool:
    return isinstance(x, dict)

@register_primitive("empty?")
def prim_is_empty(coll: Any) -> bool:
    if coll is None or coll is NIL:
        return True
    try:
        return len(coll) == 0
    except TypeError:
        return False

@register_primitive("contains?")
def prim_contains(coll: Any, key: Any) -> bool:
    if isinstance(coll, dict):
        k = key.name if isinstance(key, Keyword) else key
        return k in coll
    if isinstance(coll, (list, tuple)):
        return key in coll
    return False


# ---------------------------------------------------------------------------
# Logic (non-short-circuit versions; and/or are special forms)
# ---------------------------------------------------------------------------

@register_primitive("not")
def prim_not(x: Any) -> bool:
    return not x


# ---------------------------------------------------------------------------
# Strings
# ---------------------------------------------------------------------------

@register_primitive("str")
def prim_str(*args: Any) -> str:
    parts: list[str] = []
    for a in args:
        if a is None or a is NIL:
            parts.append("")
        elif isinstance(a, bool):
            parts.append("true" if a else "false")
        else:
            parts.append(str(a))
    return "".join(parts)

@register_primitive("concat")
def prim_concat(*colls: Any) -> list:
    result: list[Any] = []
    for c in colls:
        if c is not None and c is not NIL:
            result.extend(c)
    return result

@register_primitive("upper")
def prim_upper(s: str) -> str:
    return s.upper()

@register_primitive("lower")
def prim_lower(s: str) -> str:
    return s.lower()

@register_primitive("trim")
def prim_trim(s: str) -> str:
    return s.strip()

@register_primitive("split")
def prim_split(s: str, sep: str = " ") -> list[str]:
    return s.split(sep)

@register_primitive("join")
def prim_join(sep: str, coll: list) -> str:
    return sep.join(str(x) for x in coll)

@register_primitive("replace")
def prim_replace(s: str, old: str, new: str) -> str:
    return s.replace(old, new)

@register_primitive("strip-tags")
def prim_strip_tags(s: str) -> str:
    """Strip HTML tags from a string."""
    import re
    return re.sub(r"<[^>]+>", "", s)

@register_primitive("slice")
def prim_slice(coll: Any, start: int, end: Any = None) -> Any:
    """Slice a string or list: (slice coll start end?)."""
    start = int(start)
    if end is None or end is NIL:
        return coll[start:]
    return coll[start:int(end)]

@register_primitive("starts-with?")
def prim_starts_with(s, prefix: str) -> bool:
    if not isinstance(s, str):
        return False
    return s.startswith(prefix)

@register_primitive("ends-with?")
def prim_ends_with(s: str, suffix: str) -> bool:
    return s.endswith(suffix)


# ---------------------------------------------------------------------------
# Collections — construction
# ---------------------------------------------------------------------------

@register_primitive("list")
def prim_list(*args: Any) -> list:
    return list(args)

@register_primitive("dict")
def prim_dict(*pairs: Any) -> dict:
    result: dict[str, Any] = {}
    i = 0
    while i < len(pairs) - 1:
        key = pairs[i]
        if isinstance(key, Keyword):
            key = key.name
        result[key] = pairs[i + 1]
        i += 2
    return result

@register_primitive("range")
def prim_range(start: Any, end: Any, step: Any = 1) -> list[int]:
    return list(range(int(start), int(end), int(step)))


# ---------------------------------------------------------------------------
# Collections — access
# ---------------------------------------------------------------------------

@register_primitive("get")
def prim_get(coll: Any, key: Any, default: Any = None) -> Any:
    if isinstance(coll, dict):
        result = coll.get(key)
        if result is not None:
            return result
        if isinstance(key, Keyword):
            result = coll.get(key.name)
            if result is not None:
                return result
        return default
    if isinstance(coll, list):
        return coll[key] if 0 <= key < len(coll) else default
    return default

@register_primitive("len")
def prim_len(coll: Any) -> int:
    return len(coll)

@register_primitive("first")
def prim_first(coll: Any) -> Any:
    return coll[0] if coll else NIL

@register_primitive("last")
def prim_last(coll: Any) -> Any:
    return coll[-1] if coll else NIL

@register_primitive("rest")
def prim_rest(coll: Any) -> list:
    return coll[1:] if coll else []

@register_primitive("nth")
def prim_nth(coll: Any, n: Any) -> Any:
    return coll[n] if 0 <= n < len(coll) else NIL

@register_primitive("cons")
def prim_cons(x: Any, coll: Any) -> list:
    return [x] + list(coll) if coll else [x]

@register_primitive("append")
def prim_append(coll: Any, x: Any) -> list:
    return list(coll) + [x] if coll else [x]

@register_primitive("chunk-every")
def prim_chunk_every(coll: Any, n: Any) -> list:
    n = int(n)
    return [coll[i : i + n] for i in range(0, len(coll), n)]

@register_primitive("zip-pairs")
def prim_zip_pairs(coll: Any) -> list:
    if not coll or len(coll) < 2:
        return []
    return [[coll[i], coll[i + 1]] for i in range(len(coll) - 1)]


# ---------------------------------------------------------------------------
# Collections — dict operations
# ---------------------------------------------------------------------------

@register_primitive("keys")
def prim_keys(d: dict) -> list:
    return list(d.keys())

@register_primitive("vals")
def prim_vals(d: dict) -> list:
    return list(d.values())

@register_primitive("merge")
def prim_merge(*dicts: Any) -> dict:
    result: dict[str, Any] = {}
    for d in dicts:
        if d is not None and d is not NIL:
            result.update(d)
    return result

@register_primitive("assoc")
def prim_assoc(d: Any, *pairs: Any) -> dict:
    result = dict(d) if d and d is not NIL else {}
    i = 0
    while i < len(pairs) - 1:
        key = pairs[i]
        if isinstance(key, Keyword):
            key = key.name
        result[key] = pairs[i + 1]
        i += 2
    return result

@register_primitive("dissoc")
def prim_dissoc(d: Any, *keys_to_remove: Any) -> dict:
    result = dict(d) if d and d is not NIL else {}
    for key in keys_to_remove:
        if isinstance(key, Keyword):
            key = key.name
        result.pop(key, None)
    return result

@register_primitive("into")
def prim_into(target: Any, coll: Any) -> Any:
    if isinstance(target, list):
        if isinstance(coll, dict):
            return [[k, v] for k, v in coll.items()]
        return list(coll)
    if isinstance(target, dict):
        if isinstance(coll, dict):
            return dict(coll)
        result: dict[str, Any] = {}
        for item in coll:
            if isinstance(item, (list, tuple)) and len(item) >= 2:
                key = item[0].name if isinstance(item[0], Keyword) else item[0]
                result[key] = item[1]
        return result
    raise ValueError(f"into: unsupported target type {type(target).__name__}")


# ---------------------------------------------------------------------------
# URL helpers
# ---------------------------------------------------------------------------

@register_primitive("app-url")
def prim_app_url(service: str, path: str = "/") -> str:
    """``(app-url "blog" "/my-post/")`` → full URL for service."""
    from shared.infrastructure.urls import app_url
    return app_url(service, path)


@register_primitive("url-for")
def prim_url_for(endpoint: str, **kwargs: Any) -> str:
    """``(url-for "endpoint")`` → quart.url_for."""
    from quart import url_for
    return url_for(endpoint, **kwargs)


@register_primitive("asset-url")
def prim_asset_url(path: str = "") -> str:
    """``(asset-url "/img/logo.png")`` → versioned static URL."""
    from shared.infrastructure.urls import asset_url
    return asset_url(path)


@register_primitive("config")
def prim_config(key: str) -> Any:
    """``(config "key")`` → shared.config.config()[key]."""
    from shared.config import config
    cfg = config()
    return cfg.get(key)


@register_primitive("jinja-global")
def prim_jinja_global(key: str, default: Any = None) -> Any:
    """``(jinja-global "key")`` → current_app.jinja_env.globals[key]."""
    from quart import current_app
    return current_app.jinja_env.globals.get(key, default)


@register_primitive("relations-from")
def prim_relations_from(entity_type: str) -> list[dict]:
    """``(relations-from "page")`` → list of RelationDef dicts."""
    from shared.sx.relations import relations_from
    return [
        {
            "name": d.name, "from_type": d.from_type, "to_type": d.to_type,
            "cardinality": d.cardinality, "nav": d.nav,
            "nav_icon": d.nav_icon, "nav_label": d.nav_label,
        }
        for d in relations_from(entity_type)
    ]


# ---------------------------------------------------------------------------
# Format helpers
# ---------------------------------------------------------------------------

@register_primitive("format-date")
def prim_format_date(date_str: Any, fmt: str) -> str:
    """``(format-date date-str fmt)`` → formatted date string."""
    from datetime import datetime
    try:
        dt = datetime.fromisoformat(str(date_str))
        return dt.strftime(fmt)
    except (ValueError, TypeError):
        return str(date_str) if date_str else ""


@register_primitive("format-decimal")
def prim_format_decimal(val: Any, places: Any = 2) -> str:
    """``(format-decimal val places)`` → formatted decimal string."""
    try:
        return f"{float(val):.{int(places)}f}"
    except (ValueError, TypeError):
        return "0." + "0" * int(places)


@register_primitive("parse-int")
def prim_parse_int(val: Any, default: Any = 0) -> int | Any:
    """``(parse-int val default?)`` → int(val) with fallback."""
    try:
        return int(val)
    except (ValueError, TypeError):
        return default


@register_primitive("parse-datetime")
def prim_parse_datetime(val: Any) -> Any:
    """``(parse-datetime "2024-01-15T10:00:00")`` → datetime object."""
    from datetime import datetime
    if not val or val is NIL:
        return NIL
    return datetime.fromisoformat(str(val))


@register_primitive("split-ids")
def prim_split_ids(val: Any) -> list[int]:
    """``(split-ids "1,2,3")`` → [1, 2, 3]. Parse comma-separated int IDs."""
    if not val or val is NIL:
        return []
    return [int(x.strip()) for x in str(val).split(",") if x.strip()]


# ---------------------------------------------------------------------------
# Assertions
# ---------------------------------------------------------------------------

@register_primitive("assert")
def prim_assert(condition: Any, message: str = "Assertion failed") -> bool:
    if not condition:
        raise RuntimeError(f"Assertion error: {message}")
    return True


# ---------------------------------------------------------------------------
# Text helpers
# ---------------------------------------------------------------------------

@register_primitive("pluralize")
def prim_pluralize(count: Any, singular: str = "", plural: str = "s") -> str:
    """``(pluralize count)`` → "s" if count != 1, else "".
    ``(pluralize count "item" "items")`` → "item" or "items"."""
    try:
        n = int(count)
    except (ValueError, TypeError):
        n = 0
    if singular or plural != "s":
        return singular if n == 1 else plural
    return "" if n == 1 else "s"


@register_primitive("escape")
def prim_escape(s: Any) -> str:
    """``(escape val)`` → HTML-escaped string."""
    from markupsafe import escape as _escape
    return str(_escape(str(s) if s is not None and s is not NIL else ""))


@register_primitive("route-prefix")
def prim_route_prefix() -> str:
    """``(route-prefix)`` → service URL prefix for dev/prod routing."""
    from shared.utils import route_prefix
    return route_prefix()