// See the file "COPYING" in the main distribution directory for copyright.

// Classes for profiling CPU & memory usage by scripts.

#pragma once

#include <string>

#include "zeek/Func.h"
#include "zeek/Stmt.h"

namespace zeek {

namespace detail {

// Base class for tracking an instance of profile information.  The instance
// can be a single function body (equivalently, event handler or hook body),
// or an aggregate that includes multiple function bodies.

class ScriptProfileStats {
public:
    struct StackData {
        int call_count = 0;
        double cpu_time = 0.0;
        uint64_t memory = 0;
    };

    ScriptProfileStats() = default;
    ScriptProfileStats(std::string arg_name) : name(std::move(arg_name)) {}

    virtual ~ScriptProfileStats() = default;

    ScriptProfileStats(ScriptProfileStats&&) = default;
    ScriptProfileStats(const ScriptProfileStats&) = default;

    ScriptProfileStats& operator=(ScriptProfileStats&&) = default;
    ScriptProfileStats& operator=(const ScriptProfileStats&) = default;

    const auto Name() const { return name; }

    // Number of instances included in an aggregate (like for "all BiFs").
    // This is 1 for non-aggregates.
    int NumInstances() const { return ninstances; }

    // How many calls were profiled for this instance.
    int NumCalls() const { return ncalls; }

    // CPU & memory accumulated by the calls.
    double CPUTime() const { return CPU_time; }
    uint64_t Memory() const { return memory; }

    // Stacks for all of the calls plus counters.
    std::unordered_map<std::string, StackData> Stacks() const { return stacks; }

    // Used to count instances in an aggregate.
    void AddInstance() { ++ninstances; }

    // Fold into this profile another profile.  Second argument controls
    // whether the folding should include increasing the number of calls.
    void AddIn(const ScriptProfileStats* eps, bool bump_num_calls = true, const std::string& stack = "");

    // Accumulate a single instance of CPU & memory usage.
    void AddIn(double delta_CPU_time, uint64_t delta_memory) {
        CPU_time += delta_CPU_time;
        memory += delta_memory;
    }

    // Directly specify the total CPU & memory usage.
    void SetStats(double arg_CPU_time, uint64_t arg_memory) {
        CPU_time = arg_CPU_time;
        memory = arg_memory;
    }

    // Track that the instance has had another call.
    void NewCall() { ++ncalls; }

private:
    std::string name;
    int ninstances = 0;
    int ncalls = 0;
    double CPU_time = 0.0;
    uint64_t memory = 0;
    std::unordered_map<std::string, StackData> stacks;
};

// Manages all of the profile instances associated with a given script.

class ScriptProfile : public ScriptProfileStats {
public:
    ScriptProfile(const Func* _func, const detail::StmtPtr& body) : ScriptProfileStats(_func->GetName()) {
        func = {NewRef{}, const_cast<Func*>(_func)};
        is_BiF = body == nullptr;

        if ( is_BiF )
            loc = *func->GetLocationInfo();
        else
            loc = *body->GetLocationInfo();
    }

    // Constructor used for the special case of non-script accounting.
    ScriptProfile() : ScriptProfileStats("non-scripts") {
        func = nullptr;
        is_BiF = false;
    }

    // Called to register the beginning/end of an execution instance.
    void StartActivation();
    void EndActivation(const std::string& stack = "");

    // Called when a child instance finishes.
    void ChildFinished(const ScriptProfile* child);

    bool IsBiF() const { return is_BiF; }
    double DeltaCPUTime() const { return delta_stats.CPUTime(); }
    uint64_t DeltaMemory() const { return delta_stats.Memory(); }

    // Write the profile to the given file.
    void Report(FILE* f, bool with_traces) const;

private:
    // We store "func" as a FuncPtr to ensure it sticks around when
    // it would otherwise be ephemeral (i.e., for lambdas).
    FuncPtr func;
    bool is_BiF;
    detail::Location loc;

    // Profile associated with child instances (functions or hooks
    // that this instance calls - does not include events that this
    // instance generates).
    ScriptProfileStats child_stats;

    // These are ephemeral, only relevant between Start and End activations.
    ScriptProfileStats start_stats;

    // Defined for the last activation period.
    ScriptProfileStats delta_stats;
};

// Manages the entire script profiling process.
class ScriptProfileMgr {
public:
    // Argument specifies the file to write the profile to.
    ScriptProfileMgr(FILE* f);

    // Destructor generates the actual profile.
    ~ScriptProfileMgr();

    // Mark that the given function body has begun/finished.  "body" is
    // nil for BiFs.
    void StartInvocation(const Func* f, const detail::StmtPtr& body = nullptr);
    void EndInvocation();

    void EnableTraces() { with_traces = true; }

private:
    FILE* f; // where to write the profile

    // Separate "script" profile that tracks resource impact of non-script
    // execution.
    ScriptProfile non_scripts;

    // Currently active instances.
    std::vector<ScriptProfile*> call_stack;

    // Maps a given object (either a function body, for scripts, or the
    // function itself, for BiFs) to its profile.
    std::unordered_map<const Obj*, std::unique_ptr<ScriptProfile>> profiles;

    // Maps script bodies to their function - used for functions with
    // multiple bodies.
    std::unordered_map<const Obj*, const Func*> body_to_func;

    // Tracks the objects encountered.  Used to generate a consistent
    // and more natural printing order.
    std::vector<const Obj*> objs;

    bool with_traces = false;
};

// If non-nil, script profiling is active.
extern std::unique_ptr<ScriptProfileMgr> spm;

} // namespace detail

// Called to turn on script profiling to the given file.  If nil, writes
// the profile to stdout.
extern void activate_script_profiling(const char* fn, bool with_traces);

} // namespace zeek
