from typing import Any

from tht.mschema.eligibility import effective_eligibility
from tht.mschema.models import Annotations, ColumnAnnotation, PhysicalSchema

MAX_EXAMPLES_IN_PROMPT = 5


def _ann_col(annotations: Annotations, table: str, column: str) -> ColumnAnnotation | None:
    ann = annotations.tables.get(table)
    if ann is None:
        return None
    return ann.columns.get(column)


def _table_description(physical: PhysicalSchema, annotations: Annotations, table: str) -> str:
    ann = annotations.tables.get(table)
    if ann and ann.description:
        return ann.description
    return physical.tables[table].comment


def _column_description(
    physical: PhysicalSchema, annotations: Annotations, table: str, column: str
) -> str:
    ann = annotations.tables.get(table)
    if ann and column in ann.columns and ann.columns[column].description:
        return ann.columns[column].description
    return physical.tables[table].columns[column].comment


def to_mschema_text(
    physical: PhysicalSchema,
    annotations: Annotations | None = None,
    tables: list[str] | None = None,
) -> str:
    """Serializzazione testuale in stile ThothAI (【Schema】/【Foreign keys】)."""
    annotations = annotations or Annotations()
    selected = [t for t in physical.tables if tables is None or t in tables]
    lines: list[str] = ["【Schema】"]
    fk_lines: list[str] = []
    for table_name in selected:
        table = physical.tables[table_name]
        desc = _table_description(physical, annotations, table_name)
        if desc:
            lines.append(f"-- {desc}")
        lines.append(f"CREATE TABLE {table_name} (")
        for column_name, column in table.columns.items():
            if not effective_eligibility(column, _ann_col(annotations, table_name, column_name))[0]:
                continue
            line = f"    {column_name} {column.type.upper()}"
            if column.pk:
                line += " -- PRIMARY KEY"
            lines.append(line)
            cdesc = _column_description(physical, annotations, table_name, column_name)
            if cdesc:
                lines.append(f"    -- {cdesc}")
            if column.examples:
                shown = ", ".join(column.examples[:MAX_EXAMPLES_IN_PROMPT])
                lines.append(f"    -- Examples: {shown}")
        lines.append(");")
        for fk in table.foreign_keys:
            for src, dst in zip(fk.columns, fk.ref_columns):
                fk_lines.append(f"{table_name}.{src}={fk.ref_table}.{dst}")
    lines.extend(["", "【Foreign keys】", *fk_lines])
    return "\n".join(lines)


def to_schema_dict(
    physical: PhysicalSchema, annotations: Annotations | None = None
) -> dict[str, Any]:
    """Vista compatibile con le logiche AV-SQL (schema_dict)."""
    annotations = annotations or Annotations()
    out: dict[str, Any] = {}
    for table_name, table in physical.tables.items():
        cols = [
            c
            for c in table.columns
            if effective_eligibility(table.columns[c], _ann_col(annotations, table_name, c))[0]
        ]
        out[table_name] = {
            "columns_name": cols,
            "columns_type": [table.columns[c].type for c in cols],
            "columns_description": [
                _column_description(physical, annotations, table_name, c) for c in cols
            ],
            "example_values": [table.columns[c].examples for c in cols],
            "table_to_tablefullname": f"{physical.db_schema}.{table_name}",
            "primary_keys": [c for c in cols if table.columns[c].pk],
            "foreign_keys": [
                {"columns": fk.columns, "ref_table": fk.ref_table, "ref_columns": fk.ref_columns}
                for fk in table.foreign_keys
            ],
        }
    return out


def to_markdown(physical: PhysicalSchema, annotations: Annotations | None = None) -> str:
    """Report leggibile per il reviewer."""
    annotations = annotations or Annotations()
    lines = [
        f"# Schema {physical.db_schema} ({physical.database})",
        "",
        f"Introspezione: {physical.introspected_at.isoformat()} — "
        f"{len(physical.tables)} tabelle",
    ]
    for table_name, table in physical.tables.items():
        lines += ["", f"## {table_name}", ""]
        desc = _table_description(physical, annotations, table_name)
        if desc:
            lines += [desc, ""]
        lines += [
            f"Righe (stima): {table.row_count}",
            "",
            "| Colonna | Tipo | Null | PK | Descrizione | Esempi |",
            "|---|---|---|---|---|---|",
        ]
        for column_name, column in table.columns.items():
            eligible, reason = effective_eligibility(
                column, _ann_col(annotations, table_name, column_name)
            )
            cdesc = _column_description(physical, annotations, table_name, column_name)
            if not eligible:
                lines.append(
                    f"| ~~{column_name}~~ | {column.type} | "
                    f"{'sì' if column.nullable else 'no'} | "
                    f"{'sì' if column.pk else ''} | {cdesc} | _ignorata: {reason}_ |"
                )
                continue
            examples = ", ".join(column.examples[:3])
            lines.append(
                f"| {column_name} | {column.type} | {'sì' if column.nullable else 'no'} "
                f"| {'sì' if column.pk else ''} | {cdesc} | {examples} |"
            )
        if table.foreign_keys:
            lines += ["", "Foreign keys:"]
            for fk in table.foreign_keys:
                lines.append(
                    f"- ({', '.join(fk.columns)}) → {fk.ref_table} ({', '.join(fk.ref_columns)})"
                )
    return "\n".join(lines)