"""Index of the KiCad Visaton symbol library, and the resolver.

The library's own value strings are irregular: `MKP 1.0μF` sits next to
`MKP 10μF`, and `SP-Spule 1.0mH (0.6)` next to `LR-Spule 10mH`. Formatting a
number into a name would therefore break on some series, so the library is
parsed into `(series, value, gauge)` triples and matched numerically instead.
"""

from __future__ import annotations

import os
import re
from dataclasses import dataclass
from pathlib import Path

from .catalog import DEFAULT_SERIES, SERIES_TO_SYMBOL, Catalog
from .model import Part, PartType

#: Symbols that carry no value and are addressed by name.
AMP_SYMBOL = "Amplifier"
DRIVER_SYMBOL = "Speaker"

#: Unit suffix per component type as the library writes it.
UNIT_SUFFIX = {
    PartType.RESISTOR: "Ω",
    PartType.CAPACITOR: "μF",
    PartType.INDUCTOR: "mH",
}

#: Scale from SI to the unit the library names use.
NAME_SCALE = {
    PartType.RESISTOR: 1.0,
    PartType.CAPACITOR: 1e6,
    PartType.INDUCTOR: 1e3,
}

_SP_RE = re.compile(r"^SP-Spule\s+([\d.]+)mH\s+\(([\d.]+)\)$")
_PLAIN_RE = re.compile(r"^(.*?)\s+([\d.]+)(mH|μF|Ω)$")
_SYMBOL_RE = re.compile(r'^\s*\(symbol\s+"([^"]+)"', re.MULTILINE)
_UNIT_SUFFIX_RE = re.compile(r"_\d+_\d+$")
_EXTENDS_RE = re.compile(r'\(extends\s+"([^"]+)"\)')
_LIB_VERSION_RE = re.compile(r"\(version\s+(\d+)\)")

#: Oldest symbol library format this tool will read. KiCad 6 era libraries use
#: `(id N)` properties and bare `hide` tokens, which cannot be embedded into a
#: current schematic verbatim. `kicad-cli sym upgrade` converts them.
MIN_LIB_VERSION = 20211014


class SymbolError(ValueError):
    pass


@dataclass(frozen=True)
class LibrarySymbol:
    name: str
    series: str | None  # library-side series, e.g. "SP-Spule"
    value: float | None  # SI
    gauge: str | None  # "0.6" etc, SP inductors only


@dataclass
class Resolution:
    """The outcome of resolving one Boxsim part to a library symbol."""

    part: Part
    symbol: str
    value_text: str
    series: str | None = None
    inferred_series: bool = False
    dcr_note: str | None = None

    @property
    def notes(self) -> list[str]:
        out = []
        if self.inferred_series:
            out.append(f"series inferred as {self.series!r} (Boxsim left _bem empty)")
        if self.dcr_note:
            out.append(self.dcr_note)
        return out


def _parse_symbol_name(name: str) -> LibrarySymbol:
    m = _SP_RE.match(name)
    if m:
        return LibrarySymbol(name, "SP-Spule", float(m.group(1)) * 1e-3, m.group(2))
    m = _PLAIN_RE.match(name)
    if m:
        series, number, unit = m.group(1), float(m.group(2)), m.group(3)
        scale = {"mH": 1e-3, "μF": 1e-6, "Ω": 1.0}[unit]
        return LibrarySymbol(name, series, number * scale, None)
    return LibrarySymbol(name, None, None, None)


class SymbolLibrary:
    """Parsed `Visaton.kicad_sym`."""

    def __init__(self, path: Path, names: list[str], source: str):
        self.path = path
        self.source = source
        self.symbols = [_parse_symbol_name(n) for n in names]
        self._by_name = {s.name: s for s in self.symbols}
        self._index: dict[tuple[str, str | None], dict[int, LibrarySymbol]] = {}
        for s in self.symbols:
            if s.series is None or s.value is None:
                continue
            self._index.setdefault((s.series, s.gauge), {})[round(s.value, 12)] = s

    def __len__(self) -> int:
        return len(self.symbols)

    def __contains__(self, name: str) -> bool:
        return name in self._by_name

    @property
    def names(self) -> list[str]:
        return [s.name for s in self.symbols]

    def lookup(
        self, series: str, value: float, gauge: str | None = None, rtol: float = 1e-6
    ) -> LibrarySymbol | None:
        bucket = self._index.get((series, gauge))
        if not bucket:
            return None
        exact = bucket.get(round(value, 12))
        if exact is not None:
            return exact
        best, best_err = None, None
        for v, sym in bucket.items():
            if v == 0:
                continue
            err = abs(v - value) / v
            if err <= rtol and (best_err is None or err < best_err):
                best, best_err = sym, err
        return best

    def raw_definition(self, name: str) -> str:
        """The s-expression block for one symbol, exactly as stored."""
        needle = f'(symbol "{name}"'
        start = self.source.find(needle)
        if start < 0:
            raise SymbolError(f"symbol {name!r} not found in {self.path}")
        # Walk balanced parentheses, ignoring those inside strings. Symbol names
        # such as `SP-Spule 0.82mH (0.6)` contain parentheses of their own.
        depth, i, in_str, escaped = 0, start, False, False
        while i < len(self.source):
            ch = self.source[i]
            if in_str:
                if escaped:
                    escaped = False
                elif ch == "\\":
                    escaped = True
                elif ch == '"':
                    in_str = False
            elif ch == '"':
                in_str = True
            elif ch == "(":
                depth += 1
            elif ch == ")":
                depth -= 1
                if depth == 0:
                    return self.source[start : i + 1]
            i += 1
        raise SymbolError(f"unbalanced s-expression for symbol {name!r}")

    def base_of(self, name: str) -> str | None:
        """The symbol this one `extends`, if any."""
        m = _EXTENDS_RE.search(self.raw_definition(name))
        return m.group(1) if m else None

    def geometry_source(self, name: str) -> str:
        """The definition that actually carries pins and graphics."""
        seen = set()
        current = name
        while True:
            base = self.base_of(current)
            if base is None:
                return self.raw_definition(current)
            if base in seen:
                raise SymbolError(f"circular extends chain at {base!r}")
            seen.add(base)
            current = base

    def definition(self, name: str) -> str:
        """A self-contained symbol block suitable for a schematic's lib_symbols.

        A derived symbol is flattened: its own properties are kept and the base
        symbol's graphical sub-units are copied in under the derived name.
        KiCad never writes `extends` into a schematic cache, so neither do we.
        """
        own = self.raw_definition(name)
        base = self.base_of(name)
        if base is None:
            return own

        body = _EXTENDS_RE.sub("", own, count=1)
        closing = body.rstrip()
        if not closing.endswith(")"):
            raise SymbolError(f"malformed symbol block for {name!r}")
        body = closing[:-1].rstrip()

        base_block = self.geometry_source(base)
        units = []
        for unit_name in _SYMBOL_RE.findall(base_block):
            if not _UNIT_SUFFIX_RE.search(unit_name):
                continue
            suffix = unit_name[len(base) :] if unit_name.startswith(base) else ""
            unit_block = self._sub_block(base_block, unit_name)
            units.append(
                unit_block.replace(
                    f'(symbol "{unit_name}"', f'(symbol "{name}{suffix}"', 1
                )
            )
        if not units:
            raise SymbolError(f"base symbol {base!r} of {name!r} has no graphics")
        indented = "\n".join("\t\t" + u.replace("\n", "\n\t\t") for u in units)
        return f"{body}\n{indented}\n\t)"

    @staticmethod
    def _sub_block(text: str, name: str) -> str:
        needle = f'(symbol "{name}"'
        start = text.find(needle)
        if start < 0:
            raise SymbolError(f"sub-symbol {name!r} not found")
        depth, i, in_str, escaped = 0, start, False, False
        while i < len(text):
            ch = text[i]
            if in_str:
                if escaped:
                    escaped = False
                elif ch == "\\":
                    escaped = True
                elif ch == '"':
                    in_str = False
            elif ch == '"':
                in_str = True
            elif ch == "(":
                depth += 1
            elif ch == ")":
                depth -= 1
                if depth == 0:
                    return text[start : i + 1]
            i += 1
        raise SymbolError(f"unbalanced sub-symbol {name!r}")


def default_path() -> Path:
    env = os.environ.get("BOXSIM_KICAD_LIB")
    if env:
        p = Path(env)
        return p if p.suffix == ".kicad_sym" else p / "symbols" / "Visaton.kicad_sym"
    bundled = Path(__file__).resolve().parent / "data" / "Visaton.kicad_sym"
    if bundled.exists():
        return bundled
    return Path("/home/magdev/workspaces/other/kicad-visaton-lib/symbols/Visaton.kicad_sym")


def load(path: str | os.PathLike[str] | None = None) -> SymbolLibrary:
    p = Path(path) if path else default_path()
    if not p.exists():
        raise SymbolError(
            f"KiCad symbol library not found at {p}; "
            "set BOXSIM_KICAD_LIB to the kicad-visaton-lib checkout"
        )
    source = p.read_text(encoding="utf-8")
    m = _LIB_VERSION_RE.search(source[:400])
    if m is None:
        raise SymbolError(f"{p} has no (version ...) token; is it a symbol library?")
    version = int(m.group(1))
    if version < MIN_LIB_VERSION:
        raise SymbolError(
            f"{p} is in the legacy format (version {version}, need "
            f"{MIN_LIB_VERSION} or newer). Convert it with:\n"
            f"    kicad-cli sym upgrade --force {p}"
        )
    names = [n for n in _SYMBOL_RE.findall(source) if not _UNIT_SUFFIX_RE.search(n)]
    if not names:
        raise SymbolError(f"no symbols found in {p}")
    return SymbolLibrary(p, names, source)


def cross_check(catalog: Catalog, library: SymbolLibrary) -> list[str]:
    """Every catalogue part must exist in the library. Returns extra symbols."""
    missing = []
    matched = set()
    for part in catalog.parts:
        sym = library.lookup(part.symbol_series, part.value, part.gauge)
        if sym is None:
            missing.append(f"{part.series} {part.raw_value:g}")
        else:
            matched.add(sym.name)
    if missing:
        raise SymbolError(
            f"{len(missing)} catalogue part(s) have no library symbol: "
            + ", ".join(missing[:10])
        )
    return sorted(
        s.name
        for s in library.symbols
        if s.name not in matched and s.name not in (AMP_SYMBOL, DRIVER_SYMBOL)
    )


def _format_value(typ: PartType, value: float) -> str:
    scaled = value * NAME_SCALE[typ]
    text = f"{scaled:g}"
    return f"{text}{UNIT_SUFFIX[typ]}"


class Resolver:
    """Maps Boxsim parts onto library symbols using the Visaton catalogue."""

    def __init__(self, catalog: Catalog, library: SymbolLibrary):
        self.catalog = catalog
        self.library = library

    def _series_for(self, part: Part, siblings: list[Part]) -> tuple[str, bool]:
        """Catalogue series for a part, inferring one when `_bem` is empty."""
        if part.label:
            if part.label in SERIES_TO_SYMBOL:
                return part.label, False
            # Tolerate stray whitespace or case differences before giving up.
            for known in SERIES_TO_SYMBOL:
                if known.lower() == part.label.lower():
                    return known, False
            raise SymbolError(
                f"Part{part.slot}: series {part.label!r} is not in the Visaton "
                f"catalogue (known: {', '.join(sorted(SERIES_TO_SYMBOL))})"
            )

        # Empty _bem: prefer a sibling of the same type and value.
        for other in siblings:
            if (
                other is not part
                and other.typ == part.typ
                and other.label
                and other.value is not None
                and part.value is not None
                and abs(other.value - part.value) <= abs(part.value) * 1e-9
            ):
                return other.label, True

        fallback = DEFAULT_SERIES.get(part.typ)
        if fallback is None:
            raise SymbolError(
                f"Part{part.slot}: no series given and no sibling or default for "
                f"{part.typ.name.lower()}"
            )
        return fallback, True

    def resolve(self, part: Part, siblings: list[Part] | None = None) -> Resolution:
        siblings = siblings or []

        if part.typ == PartType.AMP_INPUT:
            return Resolution(part=part, symbol=AMP_SYMBOL, value_text="Amp")
        if part.typ == PartType.DRIVER:
            return Resolution(part=part, symbol=DRIVER_SYMBOL, value_text="")

        if part.value is None:
            raise SymbolError(f"Part{part.slot}: {part.typ.name.lower()} has no value")

        series, inferred = self._series_for(part, siblings)
        entry = self.catalog.find(series, part.value)
        if entry is None:
            near = self.catalog.nearest(series, part.value)
            offered = ", ".join(f"{p.raw_value:g}" for p in near) or "none"
            raise SymbolError(
                f"Part{part.slot}: {series} "
                f"{_format_value(part.typ, part.value)} is not stocked by Visaton; "
                f"nearest available: {offered}"
            )

        sym = self.library.lookup(entry.symbol_series, entry.value, entry.gauge)
        if sym is None:
            raise SymbolError(
                f"Part{part.slot}: catalogue part {series} {entry.raw_value:g} "
                f"has no symbol in {self.library.path.name}"
            )

        dcr_note = None
        if (
            part.dcr is not None
            and entry.dcr is not None
            and abs(part.dcr - entry.dcr) > 1e-9
        ):
            dcr_note = (
                f"DCR {part.dcr:g} Ohm differs from catalogue {entry.dcr:g} Ohm "
                "(edited in Boxsim)"
            )

        return Resolution(
            part=part,
            symbol=sym.name,
            value_text=_format_value(part.typ, part.value),
            series=series,
            inferred_series=inferred,
            dcr_note=dcr_note,
        )

    def resolve_all(self, parts: list[Part]) -> list[Resolution]:
        return [self.resolve(p, parts) for p in parts]