/*
 * (C) Copyright 2025- ECMWF and individual contributors.
 *
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
 * In applying this licence, ECMWF does not waive the privileges and immunities
 * granted to it by virtue of its status as an intergovernmental organisation nor
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 */

///
/// @file shapeOfTheEarth.h
/// @brief Deduction of the GRIB shape of the Earth.
///
/// This header defines the deduction responsible for resolving the
/// GRIB `shapeOfTheEarth` key used to describe the reference system
/// of the Earth in GRIB messages.
///
/// The deduction currently applies a fixed, deterministic value
/// corresponding to a spherical Earth with radius 6371229 m.
///
/// Deductions:
/// - extract values from input dictionaries (currently unused)
/// - apply deterministic resolution logic
/// - emit structured diagnostic logging
///
/// Deductions do NOT:
/// - infer values from MARS metadata
/// - apply configuration-based defaults
/// - validate against GRIB code tables
///
/// Error handling follows a strict fail-fast strategy with nested
/// exception propagation to preserve full diagnostic context.
///
/// Logging policy:
/// - DEFAULT: value defaulted by the deduction
///
/// @section References
/// Concept:
/// - @ref shapeOfTheEarthEncoding.h
///
/// Related deductions:
/// (none)
///
/// @ingroup mars2grib_backend_deductions
///
#pragma once

// System includes
#include <string>

// Tables
#include "metkit/mars2grib/backend/tables/shapeOfTheReferenceSystem.h"
#include "metkit/mars2grib/utils/generalUtils.h"

// Core deduction includes
#include "metkit/config/LibMetkit.h"
#include "metkit/mars2grib/utils/logUtils.h"
#include "metkit/mars2grib/utils/mars2gribExceptions.h"

namespace metkit::mars2grib::backend::deductions {

///
/// @brief Resolve the GRIB `shapeOfTheEarth` key.
///
/// @section Deduction contract
/// - Reads: none
/// - Writes: none
/// - Side effects: logging (DEFAULT)
/// - Failure mode: none (deterministic)
///
/// This deduction resolves the GRIB `shapeOfTheEarth` key by
/// applying a fixed, deterministic value corresponding to
/// a spherical Earth with radius 6371229 m.
///
/// No inference from MARS, or options dictionaries  is currently performed.
///
/// @tparam MarsDict_t Type of the MARS dictionary (unused)
/// @tparam ParDict_t  Type of the parameter dictionary (unused)
/// @tparam OptDict_t  Type of the options dictionary (unused)
///
/// @param[in] mars MARS dictionary (unused)
/// @param[in] par  Parameter dictionary (unused)
/// @param[in] opt  Options dictionary (unused)
///
/// @return
/// The resolved `ShapeOfTheReferenceSystem` enumeration value.
///
/// @note
/// This function is the **single authoritative deduction**
/// for `shapeOfTheEarth`.
///
/// @todo [owner: mds,dgov][scope: deduction][reason: extensibility][prio: low]
/// - Introduce inference or configuration-based selection when
/// non-spherical Earth representations are required.
///
template <class MarsDict_t, class ParDict_t, class OptDict_t>
tables::ShapeOfTheReferenceSystem resolve_ShapeOfTheEarth_or_throw(const MarsDict_t& mars, const ParDict_t& par,
                                                                   const OptDict_t& opt) {
    // Default value
    tables::ShapeOfTheReferenceSystem shapeOfTheEarth = tables::ShapeOfTheReferenceSystem::EarthSphericalRadius6371229;

    // Logging of the channel
    MARS2GRIB_LOG_DEFAULT([&]() {
        std::string logMsg = "`shapeOfTheEarth` defaulted from input dictionaries: value='";
        logMsg += tables::enum2name_ShapeOfTheReferenceSystem_or_throw(shapeOfTheEarth);
        logMsg += "'";
        return logMsg;
    }());

    // Success exit point
    return shapeOfTheEarth;
};

}  // namespace metkit::mars2grib::backend::deductions
