#pragma once

#include <ctime>
#include <optional>
#include <stdexcept>
#include <string>
#include <vector>

#include "Database.h"
#include "Views.h"

enum class ErrorCode { Invalid, NotFound, Exists, Database };

// What went wrong, with a message that can be shown to the user as it is.
class TrackerError : public std::runtime_error {
public:
    TrackerError(ErrorCode code, const std::string& message);

    ErrorCode code() const;

private:
    ErrorCode code_;
};

// All the rules for changing accounts and tasks. The prompt and the C API are
// both thin layers over this class. Each change appends human-readable notes
// (what the prompt prints), which takeMessages() hands over.
//
// How waits work: an account hits its limit until a time ("acc wait"). A task set
// to Wait is waiting for that: it shows Wait until then, and when the time passes
// the account stops waiting by itself and the task shows Limit reset (the
// conversation can be continued). Prompt / Testing tasks are not waiting: they
// show as they are, with "(account-waiting)" appended while the account waits.
class Tracker {
public:
    explicit Tracker(Database& db);

    const Database& database() const;

    // For tests and simulations: pretend the time is `fixedNow`. 0 = real clock.
    void setClock(std::time_t fixedNow);
    std::time_t now() const;

    std::vector<std::string> takeMessages();

    // ---- Accounts -----------------------------------------------------------
    void addAccount(const std::string& name);
    void deleteAccount(const std::string& name);
    void renameAccount(const std::string& name, const std::string& newName);

    // The account hit its limit until `until` (or a clock time such as "16:30",
    // "4:30pm"; a time that has passed today means tomorrow). Tasks set to Wait
    // follow the new time.
    void setAccountWait(const std::string& name, std::time_t until);
    void setAccountWaitText(const std::string& name, const std::string& timeText);
    // Ends the wait now: its Wait tasks become Limit reset. Returns false if the
    // account was not waiting.
    bool clearAccountWait(const std::string& name);

    // ---- Tasks --------------------------------------------------------------
    // `statusText` is what the user would type: "testing", "wait 4pm", "wait"...
    // nullopt = Prompt. "wait <time>" sets the account's wait too; "wait" alone
    // joins the account's running wait (and is an error if it is not waiting).
    void addTask(const std::string& name, const std::optional<std::string>& account,
                 const std::optional<std::string>& statusText);
    void deleteTask(const std::string& name);
    void renameTask(const std::string& name, const std::string& newName);
    void setTaskAccount(const std::string& name, const std::optional<std::string>& account);
    void setTaskStatus(const std::string& name, const std::string& statusText);
    // Returns false (and changes nothing) if the notes are the same already.
    bool setTaskNotes(const std::string& name, const std::string& notes);

    // ---- Computed views -----------------------------------------------------
    std::vector<TaskInfo> tasks() const;
    std::vector<AccountInfo> accounts() const;

private:
    static void requireName(const std::string& name);
    Status parseStatus(const std::string& text) const;
    std::string existingAccount(const std::string& name) const;
    TaskRow existingTask(const std::string& name) const;
    std::optional<std::time_t> runningWait(const std::string& account) const;
    void settle();
    int endAccountWait(const std::string& account, std::time_t endedAt);
    void note(const std::string& message);

    Database& db_;
    std::time_t fixedNow_;
    std::vector<std::string> messages_;
};