// C ABI for the magnetostatic solver (fkn): opaque doc, pipeline, mesh accessors, progress callback.
#pragma once

#include <stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

typedef struct FemmMagDoc FemmMagDoc;

// pct in 0..100, or -1 for label-only updates. label may be NULL.
typedef void (*FemmMagProgressFn)(int pct, const char* label, void* user);

// lifetime
FemmMagDoc* femm_mag_doc_new(void);
void        femm_mag_doc_free(FemmMagDoc* doc);

// progress reporting routed to the host (Rust/Iced).
void        femm_mag_doc_set_progress(FemmMagDoc* doc, FemmMagProgressFn fn, void* user);

// pipeline. each returns 1 on success, 0 on failure.
int femm_mag_doc_load_fem      (FemmMagDoc* doc, const char* path);
int femm_mag_doc_load_mesh     (FemmMagDoc* doc);
int femm_mag_doc_renumber      (FemmMagDoc* doc);
int femm_mag_doc_solve         (FemmMagDoc* doc);
int femm_mag_doc_write_results (FemmMagDoc* doc, const char* out_path);

// problem attributes after load_fem.
double femm_mag_doc_frequency    (const FemmMagDoc* doc);
int    femm_mag_doc_axisymmetric (const FemmMagDoc* doc);
double femm_mag_doc_depth        (const FemmMagDoc* doc);
double femm_mag_doc_precision    (const FemmMagDoc* doc);

// mesh, valid after load_mesh + renumber.
int  femm_mag_doc_num_nodes    (const FemmMagDoc* doc);
void femm_mag_doc_node         (const FemmMagDoc* doc, int i, double* x, double* y);
int  femm_mag_doc_num_elements (const FemmMagDoc* doc);
void femm_mag_doc_element      (const FemmMagDoc* doc, int i, int* p0, int* p1, int* p2);

// property table sizes. names live in the .fem parser / material library, not the solver runtime;
// per-block properties (mu_x, BdryFormat, etc.) get their own accessors when the GUI needs them.
int femm_mag_doc_num_materials  (const FemmMagDoc* doc);
int femm_mag_doc_num_boundaries (const FemmMagDoc* doc);
int femm_mag_doc_num_circuits   (const FemmMagDoc* doc);

// field-point sampling after solve. component selects which scalar to fetch.
typedef enum {
    FEMM_MAG_FIELD_A_RE     = 0,
    FEMM_MAG_FIELD_A_IM     = 1,
    FEMM_MAG_FIELD_BX_RE    = 2,
    FEMM_MAG_FIELD_BX_IM    = 3,
    FEMM_MAG_FIELD_BY_RE    = 4,
    FEMM_MAG_FIELD_BY_IM    = 5,
    FEMM_MAG_FIELD_B_MAG_RE = 6,
    FEMM_MAG_FIELD_B_MAG_IM = 7,
} FemmMagField;

double femm_mag_doc_field_at (const FemmMagDoc* doc, double x, double y, FemmMagField component);

#ifdef __cplusplus
}
#endif