// C ABI for the heat-flow solver (hsolv): opaque doc, pipeline, mesh accessors, progress callback.
#pragma once

#include <stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

typedef struct FemmHeatDoc FemmHeatDoc;

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

// lifetime
FemmHeatDoc* femm_heat_doc_new(void);
void         femm_heat_doc_free(FemmHeatDoc* doc);

// progress reporting routed to the host (Rust/Iced).
void         femm_heat_doc_set_progress(FemmHeatDoc* doc, FemmHeatProgressFn fn, void* user);

// pipeline. each returns 1 on success, 0 on failure.
int femm_heat_doc_load_feh     (FemmHeatDoc* doc, const char* path);
int femm_heat_doc_load_mesh    (FemmHeatDoc* doc);
int femm_heat_doc_load_prev    (FemmHeatDoc* doc);
int femm_heat_doc_renumber     (FemmHeatDoc* doc);
int femm_heat_doc_solve        (FemmHeatDoc* doc);
int femm_heat_doc_write_results(FemmHeatDoc* doc, const char* out_path);

// problem attributes after load_feh.
int    femm_heat_doc_axisymmetric (const FemmHeatDoc* doc);
double femm_heat_doc_depth        (const FemmHeatDoc* doc);
double femm_heat_doc_precision    (const FemmHeatDoc* doc);
double femm_heat_doc_dt           (const FemmHeatDoc* doc);

// mesh, valid after load_mesh + renumber.
int  femm_heat_doc_num_nodes    (const FemmHeatDoc* doc);
void femm_heat_doc_node         (const FemmHeatDoc* doc, int i, double* x, double* y);
int  femm_heat_doc_num_elements (const FemmHeatDoc* doc);
void femm_heat_doc_element      (const FemmHeatDoc* doc, int i, int* p0, int* p1, int* p2);

// property table sizes.
int femm_heat_doc_num_materials  (const FemmHeatDoc* doc);
int femm_heat_doc_num_boundaries (const FemmHeatDoc* doc);
int femm_heat_doc_num_conductors (const FemmHeatDoc* doc);

// field-point sampling after solve. component selects which scalar to fetch.
typedef enum {
    FEMM_HEAT_FIELD_T     = 0,
    FEMM_HEAT_FIELD_FX    = 1,
    FEMM_HEAT_FIELD_FY    = 2,
    FEMM_HEAT_FIELD_F_MAG = 3,
    FEMM_HEAT_FIELD_GX    = 4,
    FEMM_HEAT_FIELD_GY    = 5,
    FEMM_HEAT_FIELD_G_MAG = 6,
} FemmHeatField;

double femm_heat_doc_field_at(const FemmHeatDoc* doc, double x, double y, FemmHeatField component);

#ifdef __cplusplus
}
#endif