"""
Admin: System-CSV-Templates (csv_field_mappings, is_system=true) pflegen (Issue #21).
"""
from __future__ import annotations

from typing import Any, List, Optional

from fastapi import APIRouter, Depends, HTTPException
from pydantic import BaseModel, Field
from psycopg2.extras import Json

from auth import require_admin
from db import get_db, get_cursor, r2d
from csv_parser.core import get_csv_import_limits
from csv_parser.module_registry import get_module_definition, validate_field_mappings

router = APIRouter(prefix="/api/admin/csv-templates", tags=["admin", "csv-import"])


class CsvSystemTemplateCreate(BaseModel):
    module: str
    mapping_name: str = Field(..., min_length=1, max_length=100)
    description: Optional[str] = None
    column_signature: List[str] = Field(default_factory=list)
    delimiter: str = ","
    encoding: str = "utf-8"
    has_header: bool = True
    field_mappings: dict = Field(default_factory=dict)
    type_conversions: Optional[dict] = None


class CsvSystemTemplateUpdate(BaseModel):
    mapping_name: Optional[str] = Field(default=None, min_length=1, max_length=100)
    description: Optional[str] = None
    column_signature: Optional[List[str]] = None
    delimiter: Optional[str] = None
    encoding: Optional[str] = None
    has_header: Optional[bool] = None
    field_mappings: Optional[dict] = None
    type_conversions: Optional[dict] = None


class CsvImportLimitsBody(BaseModel):
    max_rows_per_file: int = Field(..., ge=100, le=2_000_000)
    max_file_bytes: int = Field(..., ge=10_000, le=2_147_483_648)


def _row_full(m: dict) -> dict:
    return {
        "id": m["id"],
        "module": m["module"],
        "mapping_name": m["mapping_name"],
        "description": m.get("description"),
        "column_signature": list(m["column_signature"]) if m.get("column_signature") else [],
        "delimiter": m["delimiter"],
        "encoding": m["encoding"],
        "has_header": m["has_header"],
        "field_mappings": m["field_mappings"],
        "type_conversions": m.get("type_conversions"),
        "usage_count": m.get("usage_count"),
        "success_rate": m.get("success_rate"),
        "last_used_at": m.get("last_used_at"),
        "created_at": m.get("created_at"),
        "updated_at": m.get("updated_at"),
        "is_system": m["is_system"],
    }


@router.get("/import-limits")
def admin_get_csv_import_limits(session: dict = Depends(require_admin)):
    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute("SELECT value FROM system_config WHERE key = %s", ("csv_import",))
        row = cur.fetchone()
    return get_csv_import_limits(r2d(row) if row else None)


@router.put("/import-limits")
def admin_put_csv_import_limits(body: CsvImportLimitsBody, session: dict = Depends(require_admin)):
    payload = {"max_rows_per_file": body.max_rows_per_file, "max_file_bytes": body.max_file_bytes}
    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute(
            """
            INSERT INTO system_config (key, value, updated_at)
            VALUES ('csv_import', %s, CURRENT_TIMESTAMP)
            ON CONFLICT (key) DO UPDATE
            SET value = EXCLUDED.value, updated_at = CURRENT_TIMESTAMP
            """,
            (Json(payload),),
        )
    return payload


@router.get("")
def list_system_templates(
    module: Optional[str] = None,
    session: dict = Depends(require_admin),
):
    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute(
            """
            SELECT * FROM csv_field_mappings
            WHERE is_system = true AND profile_id IS NULL
              AND (%s::text IS NULL OR module = %s)
            ORDER BY module, mapping_name
            """,
            (module, module),
        )
        rows = [r2d(r) for r in cur.fetchall()]
    return {"templates": [_row_full(m) for m in rows]}


@router.get("/{template_id}")
def get_system_template(template_id: int, session: dict = Depends(require_admin)):
    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute(
            "SELECT * FROM csv_field_mappings WHERE id = %s AND is_system = true AND profile_id IS NULL",
            (template_id,),
        )
        m = r2d(cur.fetchone())
    if not m:
        raise HTTPException(404, "System-Template nicht gefunden")
    return _row_full(m)


@router.post("")
def create_system_template(body: CsvSystemTemplateCreate, session: dict = Depends(require_admin)):
    if not get_module_definition(body.module):
        raise HTTPException(400, f"Unbekanntes Modul: {body.module}")
    try:
        validate_field_mappings(body.module, body.field_mappings)
    except ValueError as e:
        raise HTTPException(400, str(e))

    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute(
            """
            INSERT INTO csv_field_mappings (
                profile_id, is_system, module, mapping_name, description,
                column_signature, delimiter, encoding, has_header,
                field_mappings, type_conversions
            ) VALUES (
                NULL, true, %s, %s, %s, %s, %s, %s, %s, %s, %s
            ) RETURNING id
            """,
            (
                body.module,
                body.mapping_name,
                body.description,
                body.column_signature,
                body.delimiter,
                body.encoding,
                body.has_header,
                Json(body.field_mappings),
                Json(body.type_conversions) if body.type_conversions is not None else None,
            ),
        )
        new_id = cur.fetchone()["id"]
    return {"id": new_id}


@router.put("/{template_id}")
def update_system_template(
    template_id: int,
    body: CsvSystemTemplateUpdate,
    session: dict = Depends(require_admin),
):
    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute(
            "SELECT * FROM csv_field_mappings WHERE id = %s AND is_system = true AND profile_id IS NULL",
            (template_id,),
        )
        existing = r2d(cur.fetchone())
        if not existing:
            raise HTTPException(404, "System-Template nicht gefunden")

        patch: dict[str, Any] = body.model_dump(exclude_unset=True)
        if not patch:
            return _row_full(existing)

        fm = patch.get("field_mappings", existing["field_mappings"])
        if "field_mappings" in patch:
            try:
                validate_field_mappings(existing["module"], fm)
            except ValueError as e:
                raise HTTPException(400, str(e))

        fields_sql = []
        vals: list = []
        if "mapping_name" in patch:
            fields_sql.append("mapping_name = %s")
            vals.append(patch["mapping_name"])
        if "description" in patch:
            fields_sql.append("description = %s")
            vals.append(patch["description"])
        if "column_signature" in patch:
            fields_sql.append("column_signature = %s")
            vals.append(patch["column_signature"])
        if "delimiter" in patch:
            fields_sql.append("delimiter = %s")
            vals.append(patch["delimiter"])
        if "encoding" in patch:
            fields_sql.append("encoding = %s")
            vals.append(patch["encoding"])
        if "has_header" in patch:
            fields_sql.append("has_header = %s")
            vals.append(patch["has_header"])
        if "field_mappings" in patch:
            fields_sql.append("field_mappings = %s")
            vals.append(Json(patch["field_mappings"]))
        if "type_conversions" in patch:
            fields_sql.append("type_conversions = %s")
            tc = patch["type_conversions"]
            vals.append(Json(tc) if tc is not None else None)

        fields_sql.append("updated_at = CURRENT_TIMESTAMP")
        vals.append(template_id)

        cur.execute(
            f"UPDATE csv_field_mappings SET {', '.join(fields_sql)} WHERE id = %s",
            tuple(vals),
        )

        cur.execute("SELECT * FROM csv_field_mappings WHERE id = %s", (template_id,))
        m = r2d(cur.fetchone())
    return _row_full(m)


@router.delete("/{template_id}")
def delete_system_template(template_id: int, session: dict = Depends(require_admin)):
    with get_db() as conn:
        cur = get_cursor(conn)
        cur.execute(
            "DELETE FROM csv_field_mappings WHERE id = %s AND is_system = true AND profile_id IS NULL RETURNING id",
            (template_id,),
        )
        row = cur.fetchone()
        if not row:
            raise HTTPException(404, "System-Template nicht gefunden")
    return {"deleted": template_id}