"""
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 Component, Island, Keyword, Lambda, Macro, NIL, Symbol


# ---------------------------------------------------------------------------
# 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:
        from .boundary import validate_primitive
        validate_primitive(name)
        _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("eq?")
def prim_eq_identity(a: Any, b: Any) -> bool:
    """Identity equality — true only if a and b are the same object."""
    return a is b

@register_primitive("eqv?")
def prim_eqv(a: Any, b: Any) -> bool:
    """Equivalent: identity for compound types, value for atoms."""
    if a is b:
        return True
    if isinstance(a, (int, float, str, bool)) and isinstance(b, type(a)):
        return a == b
    if (a is None or a is NIL) and (b is None or b is NIL):
        return True
    return False

@register_primitive("equal?")
def prim_equal(a: Any, b: Any) -> bool:
    """Deep structural equality (same as =)."""
    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("boolean?")
def prim_is_boolean(x: Any) -> bool:
    return isinstance(x, bool)

@register_primitive("number?")
def prim_is_number(x: Any) -> bool:
    return isinstance(x, (int, float)) and not isinstance(x, bool)

@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("continuation?")
def prim_is_continuation(x: Any) -> bool:
    from .types import Continuation
    return isinstance(x, Continuation)

@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, str):
        return str(key) in coll
    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")
@register_primitive("upcase")
def prim_upper(s: str) -> str:
    return s.upper()

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

@register_primitive("string-length")
def prim_string_length(s: str) -> int:
    return len(s)

@register_primitive("substring")
def prim_substring(s: str, start: int, end: int) -> str:
    return s[int(start):int(end)]

@register_primitive("string-contains?")
def prim_string_contains(s: str, needle: str) -> bool:
    return needle in s

@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("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("index-of")
def prim_index_of(s: str, needle: str, start: int = 0) -> int:
    return str(s).find(needle, int(start))

@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
    if hasattr(coll, "get"):
        return coll.get(key, 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:
    if isinstance(x, list):
        return list(coll) + x if coll else list(x)
    return list(coll) + [x] if coll else [x]

@register_primitive("reverse")
def prim_reverse(coll: Any) -> list:
    return list(reversed(coll)) if coll else []

@register_primitive("flatten")
def prim_flatten(coll: Any) -> list:
    result = []
    for item in (coll or []):
        if isinstance(item, list):
            result.extend(item)
        else:
            result.append(item)
    return result

@register_primitive("has-key?")
def prim_has_key(d: Any, key: Any) -> bool:
    if not isinstance(d, dict):
        return False
    k = key.name if isinstance(key, Keyword) else key
    return k in d

@register_primitive("append!")
def prim_append_mut(coll: Any, x: Any) -> list:
    coll.append(x)
    return coll

@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("dict-set!")
def prim_dict_set_mut(d: Any, key: Any, val: Any) -> Any:
    if isinstance(key, Keyword):
        key = key.name
    d[key] = val
    return val


# ---------------------------------------------------------------------------
# Type introspection — platform primitives declared in eval.sx
# ---------------------------------------------------------------------------

@register_primitive("type-of")
def prim_type_of(x: Any) -> str:
    if isinstance(x, bool):
        return "boolean"
    if isinstance(x, (int, float)):
        return "number"
    if isinstance(x, str):
        return "string"
    if x is None or x is NIL:
        return "nil"
    if isinstance(x, Symbol):
        return "symbol"
    if isinstance(x, Keyword):
        return "keyword"
    if isinstance(x, list):
        return "list"
    if isinstance(x, dict):
        return "dict"
    if isinstance(x, Lambda):
        return "lambda"
    if isinstance(x, Component):
        return "component"
    if isinstance(x, Island):
        return "island"
    if isinstance(x, Macro):
        return "macro"
    return "unknown"


@register_primitive("symbol-name")
def prim_symbol_name(s: Any) -> str:
    return s.name if isinstance(s, Symbol) else str(s)


@register_primitive("keyword-name")
def prim_keyword_name(k: Any) -> str:
    return k.name if isinstance(k, Keyword) else str(k)


@register_primitive("sx-parse")
def prim_sx_parse(source: str) -> list:
    from .parser import parse_all
    return parse_all(source)


@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__}")


@register_primitive("random-int")
def prim_random_int(low: int, high: int) -> int:
    import random
    return random.randint(int(low), int(high))


@register_primitive("json-encode")
def prim_json_encode(value) -> str:
    import json
    return json.dumps(value, indent=2)