#!/usr/bin/env python3
"""Deterministically generate the small language-neutral Phase 3A bindings."""

from __future__ import annotations

import argparse
import hashlib
import json
import pathlib
import re
import subprocess
import sys
from typing import Any


ROOT = pathlib.Path(__file__).resolve().parents[1]
SCHEMA_PATH = ROOT / "schemas/control-v1.schema.json"
VERSION_PATH = ROOT / "VERSION"
COMPATIBILITY_PATH = ROOT / "compatibility.json"


def load_schema() -> tuple[dict[str, Any], str, str, dict[str, Any]]:
    raw = SCHEMA_PATH.read_bytes()
    schema = json.loads(raw)
    version = VERSION_PATH.read_text(encoding="utf-8").strip()
    if not re.fullmatch(r"\d+\.\d+\.\d+", version):
        raise ValueError("VERSION must be semantic version text")
    compatibility = json.loads(COMPATIBILITY_PATH.read_text(encoding="utf-8"))
    for key in ("current", "n_minus_1", "n_minus_2"):
        if not isinstance(compatibility.get(key), str):
            raise ValueError("compatibility declaration is incomplete")
    return schema, hashlib.sha256(raw).hexdigest(), version, compatibility


def pascal(name: str) -> str:
    return "".join(part[:1].upper() + part[1:] for part in re.split(r"[_-]", name))


def go_field(name: str) -> str:
    initialisms = {"api": "API", "http": "HTTP", "id": "ID", "ip": "IP", "sha": "SHA", "ttl": "TTL", "url": "URL", "uuid": "UUID"}
    return "".join(
        initialisms.get(part, part[:1].upper() + part[1:])
        for part in re.split(r"[_-]", name)
    )


def camel(name: str) -> str:
    parts = re.split(r"[_-]", name)
    return parts[0] + "".join(part[:1].upper() + part[1:] for part in parts[1:])


def swift_field(name: str) -> str:
    value = camel(name)
    if value in {"protocol", "class", "struct", "enum", "extension", "private", "public", "internal", "fileprivate", "open", "func", "let", "var", "import", "switch", "case", "default", "operator", "where", "repeat", "return", "throw", "throws", "try", "catch", "defer", "in", "is", "as"}:
        return value + "Value"
    return value


RUST_KEYWORDS = {
    "as", "break", "const", "continue", "crate", "else", "enum", "extern",
    "false", "fn", "for", "if", "impl", "in", "let", "loop", "match", "mod",
    "move", "mut", "pub", "ref", "return", "self", "Self", "static", "struct",
    "super", "trait", "true", "type", "unsafe", "use", "where", "while", "async",
    "await", "dyn", "abstract", "become", "box", "do", "final", "macro", "override",
    "priv", "typeof", "unsized", "virtual", "yield", "try", "union",
}


def rust_field(name: str) -> str:
    value = camel(name)
    return value + "Value" if value in RUST_KEYWORDS else value


def ref_name(value: Any) -> str | None:
    if isinstance(value, dict) and isinstance(value.get("$ref"), str):
        return value["$ref"].split("/")[-1]
    return None


def prop_type(prop: dict[str, Any], language: str) -> str:
    reference = ref_name(prop)
    if reference:
        return reference if language == "go" else (reference if language == "rust" else reference)
    if prop.get("type") == "array":
        item = prop.get("items", {})
        item_type = prop_type(item, language)
        if language == "go":
            return f"[]{item_type}"
        if language == "rust":
            return f"Vec<{item_type}>"
        return f"[{item_type}]"
    if prop.get("type") == "integer":
        return "int64" if language == "go" else ("i64" if language == "rust" else "Int64")
    if prop.get("type") == "boolean":
        return "bool" if language != "swift" else "Bool"
    if prop.get("type") == "object":
        return "map[string]any" if language == "go" else ("JsonObject" if language == "rust" else "JSONObject")
    return "string" if language == "go" else ("String" if language == "rust" else "String")


def go_zero(prop: dict[str, Any], field: str) -> str:
    typ = prop_type(prop, "go")
    if typ in {"string", "int64", "bool"}:
        zero = {"string": '""', "int64": "0", "bool": "false"}[typ]
        return f"v.{field} == {zero}"
    if typ.startswith("[]"):
        return f"v.{field} == nil"
    if typ == "map[string]any":
        return f"v.{field} == nil"
    return f"reflect.DeepEqual(v.{field}, {typ}{{}})"


def go_validation(definition: dict[str, Any]) -> list[str]:
    lines: list[str] = []
    name = definition["name"]
    required = set(definition.get("required", []))
    for prop_name, prop in definition.get("properties", {}).items():
        field = go_field(prop_name)
        required_zero_is_valid = prop.get("type") == "integer" and prop.get("minimum") == 0
        if prop_name in required and prop.get("type") != "boolean" and not required_zero_is_valid:
            zero = go_zero(prop, field)
            lines.append(f"\tif {zero} {{ violations = append(violations, FieldViolation{{Field: \"{prop_name}\", Code: \"required\"}}) }}")
        if prop.get("type") == "string":
            if "minLength" in prop:
                lines.append(f"\tif len(v.{field}) < {prop['minLength']} && v.{field} != \"\" {{ violations = append(violations, FieldViolation{{Field: \"{prop_name}\", Code: \"min_length\"}}) }}")
            if "maxLength" in prop:
                lines.append(f"\tif len(v.{field}) > {prop['maxLength']} {{ violations = append(violations, FieldViolation{{Field: \"{prop_name}\", Code: \"max_length\"}}) }}")
            if "const" in prop:
                lines.append(f"\tif v.{field} != \"{prop['const']}\" && v.{field} != \"\" {{ violations = append(violations, FieldViolation{{Field: \"{prop_name}\", Code: \"invalid_value\"}}) }}")
            if "enum" in prop:
                allowed = " || ".join(f'v.{field} == "{value}"' for value in prop["enum"])
                lines.append(f"\tif v.{field} != \"\" && !({allowed}) {{ violations = append(violations, FieldViolation{{Field: \"{prop_name}\", Code: \"invalid_value\"}}) }}")
            if prop.get("format") == "date-time":
                lines.append(
                    '\tif v.%s != "" { if parsed, err := time.Parse(time.RFC3339Nano, v.%s); err != nil || parsed.UTC().Format(time.RFC3339Nano) != v.%s { violations = append(violations, FieldViolation{Field: "%s", Code: "invalid_time"}) } }'
                    % (field, field, field, prop_name)
                )
        if prop.get("type") == "integer":
            if "minimum" in prop:
                lines.append(f"\tif v.{field} != 0 && v.{field} < {prop['minimum']} {{ violations = append(violations, FieldViolation{{Field: \"{prop_name}\", Code: \"minimum\"}}) }}")
            if "maximum" in prop:
                lines.append(f"\tif v.{field} > {prop['maximum']} {{ violations = append(violations, FieldViolation{{Field: \"{prop_name}\", Code: \"maximum\"}}) }}")
        if prop.get("type") == "array":
            if "minItems" in prop:
                lines.append(f"\tif len(v.{field}) < {prop['minItems']} {{ violations = append(violations, FieldViolation{{Field: \"{prop_name}\", Code: \"min_items\"}}) }}")
            if "maxItems" in prop:
                lines.append(f"\tif len(v.{field}) > {prop['maxItems']} {{ violations = append(violations, FieldViolation{{Field: \"{prop_name}\", Code: \"max_items\"}}) }}")
            item_ref = ref_name(prop.get("items", {}))
            if item_ref:
                lines.append(f"\tfor index := range v.{field} {{ if err := v.{field}[index].Validate(); err != nil {{ violations = append(violations, FieldViolation{{Field: fmt.Sprintf(\"{prop_name}[%d]\", index), Code: \"invalid_item\"}}) }} }}")
        reference = ref_name(prop)
        if reference:
            lines.append(f"\tif err := v.{field}.Validate(); err != nil {{ violations = append(violations, FieldViolation{{Field: \"{prop_name}\", Code: \"invalid_object\"}}) }}")
    return lines


def generate_go(defs: dict[str, dict[str, Any]], schema_hash: str, version: str, compatibility: dict[str, Any]) -> str:
    out = [
        "// Code generated by tools/generate.py; DO NOT EDIT.",
        "package protocol",
        "",
        "import (",
        "\"bytes\"",
        "\"encoding/json\"",
        "\"errors\"",
        "\"fmt\"",
        "\"reflect\"",
        "\"time\"",
        ")",
        "",
        f'const SchemaSHA256 = "{schema_hash}"',
        f'const ProtocolVersion = "{version}"',
        f'const CurrentWireVersion = "{compatibility["current"]}"',
        f'const NMinus1WireVersion = "{compatibility["n_minus_1"]}"',
        f'const NMinus2WireVersion = "{compatibility["n_minus_2"]}"',
        "",
        "type FieldViolation struct {",
        "\tField string `json:\"field\"`",
        "\tCode string `json:\"code\"`",
        "}",
        "",
        "type ValidationError struct {",
        "\tViolations []FieldViolation",
        "}",
        "",
        "func (e ValidationError) Error() string { return \"protocol validation failed\" }",
        "",
    ]
    for name in sorted(defs):
        if name == "FieldViolation":
            continue
        definition = defs[name]
        out.append(f"type {name} struct {{")
        required = set(definition.get("required", []))
        for prop_name, prop in definition.get("properties", {}).items():
            tag = prop_name + (",omitempty" if prop_name not in required else "")
            out.append(f"\t{go_field(prop_name)} {prop_type(prop, 'go')} `json:\"{tag}\"`")
        out.extend(["}", ""])
    for name in sorted(defs):
        out.append(f"func (v {name}) Validate() error {{")
        out.append("\tvar violations []FieldViolation")
        out.extend(go_validation(defs[name]))
        out.append("\tif len(violations) > 0 { return ValidationError{Violations: violations} }")
        out.append("\treturn nil")
        out.append("}")
        out.append("")
        out.append(f"func Decode{name}(data []byte) ({name}, error) {{")
        out.append(f"\tvar value {name}")
        out.append("\tif len(data) > 1024*1024 { return value, errors.New(\"protocol payload exceeds limit\") }")
        out.append("\tvar fields map[string]json.RawMessage")
        out.append("\tif err := json.Unmarshal(data, &fields); err != nil { return value, err }")
        required_fields = sorted(defs[name].get("required", []))
        for prop_name in required_fields:
            out.append(
                '\tif raw, ok := fields["%s"]; !ok || bytes.Equal(bytes.TrimSpace(raw), []byte("null")) { return value, ValidationError{Violations: []FieldViolation{{Field: "%s", Code: "required"}}} }'
                % (prop_name, prop_name)
            )
        for prop_name, prop in defs[name].get("properties", {}).items():
            if "x-max-bytes" in prop:
                out.append(
                    '\tif raw, ok := fields["%s"]; ok && len(raw) > %d { return value, ValidationError{Violations: []FieldViolation{{Field: "%s", Code: "max_bytes"}}} }'
                    % (prop_name, prop["x-max-bytes"], prop_name)
                )
        out.append("\tdecoder := json.NewDecoder(bytes.NewReader(data))")
        out.append("\tdecoder.DisallowUnknownFields()")
        out.append("\tif err := decoder.Decode(&value); err != nil { return value, err }")
        out.append("\tvar trailing any")
        out.append("\tif err := decoder.Decode(&trailing); err != io.EOF { if err == nil { return value, errors.New(\"trailing JSON value\") }; return value, err }")
        out.append("\tif err := value.Validate(); err != nil { return value, err }")
        out.append("\treturn value, nil")
        out.append("}")
        out.append("")
        out.append(f"func Encode{name}(value {name}) ([]byte, error) {{")
        out.append("\tif err := value.Validate(); err != nil { return nil, err }")
        out.append("\treturn json.Marshal(value)")
        out.append("}")
        out.append("")
    # Use io.EOF in generated code without making every generated decoder depend on
    # error-string comparison; replace the deliberately compact placeholder.
    text = "\n".join(out).replace('"errors"\n"fmt"', '"errors"\n"fmt"\n\"io"')
    text = text.replace('!errors.Is(err, errors.New("EOF")) && err != nil', '!errors.Is(err, io.EOF)')
    return text + "\n"


def rust_type(prop: dict[str, Any]) -> str:
    reference = ref_name(prop)
    if reference:
        return reference
    if prop.get("type") == "array":
        return f"Vec<{rust_type(prop.get('items', {}))}>"
    if prop.get("type") == "integer":
        return "i64"
    if prop.get("type") == "boolean":
        return "bool"
    if prop.get("type") == "object":
        return "JsonObject"
    return "String"


def swift_type(prop: dict[str, Any]) -> str:
    reference = ref_name(prop)
    if reference:
        return reference
    if prop.get("type") == "array":
        return f"[{swift_type(prop.get('items', {}))}]"
    if prop.get("type") == "integer":
        return "Int64"
    if prop.get("type") == "boolean":
        return "Bool"
    if prop.get("type") == "object":
        return "JSONObject"
    return "String"


def generate_rust(defs: dict[str, dict[str, Any]], schema_hash: str, compatibility: dict[str, Any]) -> str:
    out = [
        "// Code generated by tools/generate.py; DO NOT EDIT.",
        "#![allow(non_snake_case)]",
        "pub const SCHEMA_SHA256: &str = \"" + schema_hash + "\";",
        f'pub const CURRENT_WIRE_VERSION: &str = "{compatibility["current"]}";',
        f'pub const N_MINUS_1_WIRE_VERSION: &str = "{compatibility["n_minus_1"]}";',
        f'pub const N_MINUS_2_WIRE_VERSION: &str = "{compatibility["n_minus_2"]}";',
        "pub type JsonObject = std::collections::BTreeMap<String, String>;",
        "",
    ]
    for name in sorted(defs):
        definition = defs[name]
        out.extend(["#[derive(Debug, Clone, PartialEq, Eq)]", f"pub struct {name} {{"])
        required = set(definition.get("required", []))
        for prop_name, prop in definition.get("properties", {}).items():
            field = rust_field(prop_name)
            typ = rust_type(prop)
            if prop_name not in required:
                typ = f"Option<{typ}>"
            out.append(f"    pub {field}: {typ},")
        out.extend(["}", ""])
    return "\n".join(out)


def generate_swift(defs: dict[str, dict[str, Any]], schema_hash: str, compatibility: dict[str, Any]) -> str:
    out = [
        "// Code generated by tools/generate.py; DO NOT EDIT.",
        "import Foundation",
        "public typealias JSONObject = [String: String]",
        f"public let schemaSHA256 = \"{schema_hash}\"",
        f'public let currentWireVersion = "{compatibility["current"]}"',
        f'public let nMinus1WireVersion = "{compatibility["n_minus_1"]}"',
        f'public let nMinus2WireVersion = "{compatibility["n_minus_2"]}"',
        "",
    ]
    for name in sorted(defs):
        definition = defs[name]
        required = set(definition.get("required", []))
        out.extend(["public struct " + name + ": Codable, Equatable {",])
        for prop_name, prop in definition.get("properties", {}).items():
            typ = swift_type(prop)
            if prop_name not in required:
                typ += "?"
            out.append(f"    public let {swift_field(prop_name)}: {typ}")
        out.append("    enum CodingKeys: String, CodingKey {")
        for prop_name in definition.get("properties", {}):
            out.append(f"        case {swift_field(prop_name)} = \"{prop_name}\"")
        out.extend(["    }", "", "    public init(from decoder: Decoder) throws {",])
        out.append("        let c = try decoder.container(keyedBy: CodingKeys.self)")
        for prop_name, prop in definition.get("properties", {}).items():
            field = swift_field(prop_name)
            typ = swift_type(prop)
            if prop_name in required:
                out.append(f"        {field} = try c.decode({typ}.self, forKey: .{field})")
            else:
                out.append(f"        {field} = try c.decodeIfPresent({typ}.self, forKey: .{field})")
        out.extend(["    }", "}", ""])
    return "\n".join(out)


def write_or_check(path: pathlib.Path, content: str, check: bool) -> None:
    if check:
        if not path.exists() or path.read_text(encoding="utf-8") != content:
            raise ValueError(f"generated output differs: {path.relative_to(ROOT)}")
        return
    path.parent.mkdir(parents=True, exist_ok=True)
    path.write_text(content, encoding="utf-8")


def format_go(content: str) -> str:
    result = subprocess.run(["gofmt"], input=content, text=True, capture_output=True, check=False)
    if result.returncode != 0:
        raise ValueError(f"gofmt failed: {result.stderr.strip()}")
    return result.stdout


def main() -> int:
    parser = argparse.ArgumentParser()
    parser.add_argument("--check", action="store_true")
    args = parser.parse_args()
    schema, schema_hash, version, compatibility = load_schema()
    generator_hash = hashlib.sha256(pathlib.Path(__file__).read_bytes()).hexdigest()
    defs = schema.get("$defs")
    if not isinstance(defs, dict) or not defs:
        raise ValueError("schema must contain non-empty $defs")
    normalized = {name: dict(value, name=name) for name, value in defs.items()}
    outputs = {
        ROOT / "gen/go/protocol/protocol.go": format_go(generate_go(normalized, schema_hash, version, compatibility)),
        ROOT / "gen/rust/protocol.rs": generate_rust(normalized, schema_hash, compatibility).rstrip() + "\n",
        ROOT / "gen/swift/Protocol.swift": generate_swift(normalized, schema_hash, compatibility).rstrip() + "\n",
        ROOT / "gen/manifest.json": json.dumps({
            "generator_sha256": generator_hash,
            "schema_sha256": schema_hash,
            "protocol_version": version,
            "compatibility": compatibility,
        }, sort_keys=True, indent=2) + "\n",
    }
    for path, content in outputs.items():
        write_or_check(path, content, args.check)
    return 0


if __name__ == "__main__":
    try:
        raise SystemExit(main())
    except (OSError, ValueError, json.JSONDecodeError) as exc:
        print(f"generate: {exc}", file=sys.stderr)
        raise SystemExit(1)