#ifndef FUNCTION_MANAGER_H
#define FUNCTION_MANAGER_H

#include "lib/context.h"
#include "lib/mlrval.h"
#include "containers/lhmsv.h"
#include "containers/hss.h"
#include "dsl/mlr_dsl_ast.h"
#include "dsl/rval_evaluator.h"
#include "dsl/rxval_evaluator.h"
#include "dsl/type_inference.h"

// ----------------------------------------------------------------
// Things a user-defined function (however it is implemented) needs in order to
// be called: pvstate is its own state (whatever that is), and it defines its
// own process and free functions implementing this interface.

typedef boxed_xval_t udf_defsite_process_func_t(void* pvstate, int arity, boxed_xval_t* pargs, variables_t* pvars);
typedef void udf_defsite_free_func_t(void* pvstate, context_t* pctx);

typedef struct _udf_defsite_state_t {
	void* pvstate;
	char* name;
	int   arity;
	udf_defsite_process_func_t* pprocess_func;
	udf_defsite_free_func_t* pfree_func;
} udf_defsite_state_t;

// ----------------------------------------------------------------
// Holds built-in functions as well as user-defined functions

struct _function_lookup_t; // Private to the .c file
typedef struct _fmgr_t {
	struct _function_lookup_t * function_lookup_table; // Built-ins
	hss_t* built_in_function_names;                    // Built-ins
	lhmsv_t* pudf_names_to_defsite_states;             // UDF bodies
	// Function callsites, used to bootstrap (e.g. function f calls function g before the latter
	// has been defined).
	sllv_t* pfunc_callsite_evaluators_to_resolve;  // return value in scalar context
	sllv_t* pfunc_callsite_xevaluators_to_resolve; // return value in map context
} fmgr_t;

// ----------------------------------------------------------------
fmgr_t* fmgr_alloc();

void fmgr_free(fmgr_t* pfmgr, context_t* pctx);

void fmgr_install_udf(fmgr_t* pfmgr, udf_defsite_state_t* pdefsitate_state);

// Callsites as defined by AST nodes, with scalar-context return values
rval_evaluator_t* fmgr_alloc_provisional_from_operator_or_function_call(fmgr_t* pfmgr, mlr_dsl_ast_node_t* pnode,
	int type_inferencing, int context_flags);
// Callsites as defined by AST nodes, with map-context return values
rxval_evaluator_t* fmgr_xalloc_provisional_from_operator_or_function_call(fmgr_t* pfmgr, mlr_dsl_ast_node_t* pnode,
	int type_inferencing, int context_flags);

void fmgr_mark_callsite_to_resolve(fmgr_t* pfmgr, rval_evaluator_t* pev);
void fmgr_mark_xcallsite_to_resolve(fmgr_t* pfmgr, rxval_evaluator_t* pxev);
// Update all function callsites to point to UDF bodies, once all the latter have been defined.
void fmgr_resolve_func_callsites(fmgr_t* pfmgr);

//  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
void fmgr_list_functions(fmgr_t* pfmgr, FILE* output_stream, char* leader);

// Pass function_name == NULL to get usage for all functions:
void fmgr_function_usage(fmgr_t* pfmgr, FILE* output_stream, char* function_name);

void fmgr_list_all_functions_raw(fmgr_t* pfmgr, FILE* output_stream);

#endif // FUNCTION_MANAGER_H
