/*
* Copyright (c) 2025 Aldrik Ramaekers <aldrik.ramaekers@gmail.com>
* 
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
* 
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include <time.h>
#include <ImGuiDatePicker/ImGuiDatePicker.hpp>

#include "ui.hpp"
#include "imgui.h"
#include "memops.hpp"
#include "strops.hpp"
#include "locales.hpp"
#include "importer.hpp"
#include "administration.hpp"
#include "administration_writer.hpp"

static activity* activity_buffer = 0;
static u32 activity_count;

static importer::invoice_request* active_import_request = 0;

static ui::view_state current_view_state = ui::view_state::LIST_ALL;
static invoice active_invoice = {0};
static invoice selected_for_removal = {0};
static const float sidepanel_width = 200.0f;
static billing_item* invoice_items_buffer = 0;

void draw_invoice_items_form(invoice* invoice, bool outgoing = true);

static void _reload_activities()
{
    activity_count = administration::activity_get_all_for_object(activity_buffer, active_invoice.id);
}

static void _set_active_invoice(invoice inv)
{
    active_invoice = inv;
    _reload_activities();
}

void ui::destroy_expenses()
{
    memops::unalloc(invoice_items_buffer);
    memops::unalloc(activity_buffer);
}

void ui::setup_expenses()
{
    if (active_import_request != 0) {
        current_view_state = ui::view_state::VIEW_IMPORT_REQUEST;
    }
    else {
        current_view_state = ui::view_state::LIST_ALL;
    }

    activity_buffer = (activity*)memops::alloc(sizeof(activity) * 250);
    _set_active_invoice(administration::invoice_create_empty());

    u32 invoice_items_count = MAX_BILLING_ITEMS;
    invoice_items_buffer = (billing_item*)memops::alloc(sizeof(billing_item) * invoice_items_count);
}

static void draw_expense_form(invoice* buffer, bool viewing_only = false)
{
    if (viewing_only) ImGui::BeginDisabled();

    ImGui::Text("%s: %s", locale::get("invoice.form.invoicenumber"), buffer->sequential_number);
    //ImGui::Text("%s: %s", locale::get("invoice.form.billedTo"), buffer->customer.name);

    tm issued_at_date = *gmtime(&buffer->issued_at);
    if (ImGui::DatePicker("##issuedAt", issued_at_date))
    {
        buffer->issued_at = mktime(&issued_at_date);
    }
    ImGui::SameLine();
    ImGui::Text(locale::get("invoice.form.issuedat"));

    tm expires_at_date = *gmtime(&buffer->expires_at);
    if (ImGui::DatePicker("##expiresAt", expires_at_date))
    {
        buffer->expires_at = mktime(&expires_at_date);
    }
    ImGui::SameLine();
    ImGui::Text(locale::get("invoice.form.expiresat"));

    tm delivered_at_date = *gmtime(&buffer->delivered_at);
    if (ImGui::DatePicker("##deliveredAt", delivered_at_date))
    {
        buffer->delivered_at = mktime(&delivered_at_date);
    }
    ImGui::SameLine();
    ImGui::Text(locale::get("invoice.form.deliveredat"));

    ImGui::Separator();

    if (ImGui::FileSelect(locale::get("ui.fileselect.text"), buffer->document.original_path)) {
        buffer->document.copy_path[0] = 0;
    }

    ImGui::Separator();

    ImGui::Text(locale::get("invoice.form.billinginformation"));
    ImGui::ContactForm(&buffer->customer, false, true, false);

    ImGui::Separator();

    ImGui::Text(locale::get("invoice.form.supplier"));
    ImGui::ContactForm(&buffer->supplier, false, true, false);

    ImGui::Checkbox(locale::get("invoice.form.triangulation"), &buffer->is_triangulation);
    if (buffer->is_triangulation) {
        ImGui::Spacing();
        ImGui::Text(locale::get("invoice.form.shippinginformation"));
        ImGui::DeliveryInfoForm(&buffer->addressee, 0);
    }
    ImGui::Separator();

    ImGui::ProjectDropdown(buffer->project_id);
    ImGui::CostCenterDropdown(buffer->cost_center_id);

    ImGui::Separator();

    ImGui::Spacing();
    ImGui::Spacing();
    ImGui::Spacing();

    bool max_items_reached = administration::billing_item_count(buffer) >= MAX_BILLING_ITEMS;
    if (max_items_reached) ImGui::BeginDisabled();
    if (ImGui::Button(locale::get(locale::get("invoice.form.add"))))
    {
        billing_item item = administration::billing_item_create_empty();
        administration::billing_item_add_to_invoice(buffer, item);
    }
    if (max_items_reached) ImGui::EndDisabled();

    ImGui::SameLine();
    ImGui::Text("| %s: ", locale::get("invoice.form.currency"));
    ImGui::SameLine();
    if (ImGui::CurrencyDropdown(buffer->currency))
    {
        administration::invoice_set_currency(buffer, buffer->currency);
    }

    draw_invoice_items_form(buffer, false);

    if (viewing_only) ImGui::EndDisabled();
}

static void draw_expenses_list()
{
    if (!administration::can_create_invoices()) {
        ImGui::PushStyleColor(ImGuiCol_Text, IM_COL32(0, 102, 204, 255)); // blue
        ImGui::Text(locale::get("ui.invoiceRequirementP1"));
        ImGui::PopStyleColor();

        if (ImGui::IsItemHovered()) {
            ImGui::SetMouseCursor(ImGuiMouseCursor_Hand);
            if (ImGui::IsMouseClicked(ImGuiMouseButton_Left)) {
                ui::set_state(ui::main_state::UI_SETTINGS);
            }
        }

        ImGui::SameLine();
        ImGui::Text(locale::get("ui.invoiceRequirementP2"));
        return;
    }

    const u32 items_per_page = 50;
    static s32 current_page = 0;

    invoice invoice_list[items_per_page];
    u32 invoice_count = administration::invoice_get_partial_list_incomming(current_page, items_per_page, invoice_list);
    u32 total_invoice_count = administration::invoice_get_incomming_count();

    s32 max_page = (total_invoice_count + items_per_page - 1) / items_per_page;
    if (max_page == 0) max_page = 1;

    // Table header controls: create, import, and pagination.
    if (ImGui::Button(locale::get("form.create")))
    {
        current_view_state = ui::view_state::CREATE;
        active_invoice = administration::invoice_create_empty();
        active_invoice.customer = administration::company_info_get();
        active_invoice.is_outgoing = 0;
        active_invoice.status = invoice_status::INVOICE_RECEIVED;
    }

    char import_file_path[MAX_LEN_PATH] = {0};
    ImGui::SameLine();
    if (ImGui::FileSelect(locale::get("ui.import"), import_file_path)) {
        current_view_state = ui::view_state::VIEW_IMPORT_REQUEST;
        active_invoice = administration::invoice_create_empty();
        active_invoice.customer = administration::company_info_get();
        active_invoice.is_outgoing = 0;
        active_invoice.status = invoice_status::INVOICE_RECEIVED;

        active_import_request = importer::ai_document_to_invoice(import_file_path);
    }

    if (current_page >= max_page-1) current_page = max_page-1;
    if (current_page < 0) current_page = 0;

    // Navigate to prev page button.
    ImGui::SameLine();
    bool enable_prev = current_page > 0;
    if (!enable_prev) ImGui::BeginDisabled();
    if (ImGui::Button(locale::get("ui.prev")) && current_page > 0) current_page--;
    if (!enable_prev) ImGui::EndDisabled();

    ImGui::SameLine();
    ImGui::Text("(%d/%d)", current_page+1, max_page);

    // Navigate to next page button.
    ImGui::SameLine();
    bool enable_next = current_page < max_page-1;
    if (!enable_next) ImGui::BeginDisabled();
    if (ImGui::Button(locale::get("ui.next")) && current_page < max_page-1) current_page++;
    if (!enable_next) ImGui::EndDisabled();

    ImGui::Spacing();

    if (ImGui::BeginTable("TableInvoices", 6, ImGuiTableFlags_Borders | ImGuiTableFlags_RowBg)) {

        ImGui::TableSetupColumn(locale::get("invoice.table.invoicenumber"), ImGuiTableColumnFlags_WidthFixed, 120);
        ImGui::TableSetupColumn(locale::get("invoice.table.sender"));
        ImGui::TableSetupColumn(locale::get("invoice.table.customer"));
        ImGui::TableSetupColumn(locale::get("invoice.table.issuedat"), ImGuiTableColumnFlags_WidthFixed, 90);
        ImGui::TableSetupColumn(locale::get("invoice.table.total"), ImGuiTableColumnFlags_WidthFixed, 90);
        ImGui::TableSetupColumn(locale::get("invoice.table.status"), ImGuiTableColumnFlags_WidthFixed, 90);
        ImGui::TableHeadersRow();

        for (u32 i = 0; i < invoice_count; i++) {
            invoice c = invoice_list[i];
            
            ImGui::TableNextRow();
            ImGui::TableSetColumnIndex(0); 
            
            ImGui::PushID(i);
            ImGuiSelectableFlags selectable_flags = ImGuiSelectableFlags_SpanAllColumns | ImGuiSelectableFlags_AllowOverlap;
            bool selected = false;
            if (ImGui::Selectable("##invisible_selectable", selected, selectable_flags, ImVec2(0, ImGui::GetFrameHeight()-4.0f)))
            {
                _set_active_invoice(c);
                current_view_state = ui::view_state::VIEW_EXISTING;
            }
            ImGui::SetItemAllowOverlap();
            ImGui::SameLine();
            ImGui::PopID();
            
            ImGui::Text(c.sequential_number);

            if (administration::invoice_is_valid(&c) != A_ERR_SUCCESS)
            {
                if (ImGui::WarningIcon(8.0f)) {
                    ImGui::SetTooltip(locale::get("ui.tooltip.invalidInvoice"));
                }
            }

            ImGui::TableSetColumnIndex(1); ImGui::Text(c.supplier.name);
            ImGui::TableSetColumnIndex(2); ImGui::Text(c.customer.name);

            struct tm *lt = localtime(&c.issued_at);
            char buf[80];
            strftime(buf, sizeof(buf), "%d-%m-%Y", lt);

            ImGui::TableSetColumnIndex(3); ImGui::Text(buf);
            ImGui::TableSetColumnIndex(4); ImGui::Text("%.2f %s", c.total, c.currency);
            ImGui::TableSetColumnIndex(5); ImGui::Text("%s", locale::get(administration::invoice_get_status_string(&c)));
            
            /*
            char btn_name[20];
            strops::format(btn_name, sizeof(btn_name), "%s##%d", locale::get("form.view"), i);
            if (ImGui::Button(btn_name)) {
                active_invoice = c;
                current_view_state = ui::view_state::VIEW_EXISTING;
            }

            ImGui::SameLine();

            strops::format(btn_name, sizeof(btn_name), "%s##%d", locale::get("form.change"), i);
            if (ImGui::Button(btn_name)) {
                active_invoice = administration::invoice_create_copy(&c); // We create a copy because of billing item list pointers.
                current_view_state = ui::view_state::EDIT_EXISTING;
            }
            
            ImGui::SameLine();
            strops::format(btn_name, sizeof(btn_name), "%s##%d", locale::get("form.delete"), i);
            if (ImGui::Button(btn_name)) {
                selected_for_removal = c;
                ImGui::OpenPopup("ConfirmDeletePopup");
            }*/
        }

        ImGui::EndTable();
    }
}

static void _reset_to_default_view()
{
    current_view_state = ui::view_state::LIST_ALL;
    ui::destroy_expenses();
    ui::setup_expenses();
    activity_count = 0;
}

static void _reset_to_invoice_view()
{
    current_view_state = ui::view_state::VIEW_EXISTING;
}

static void _draw_activity_sidepanel()
{
    ImGui::SameLine();
    ImGui::SeparatorEx(1 << 1, 3.0f);
    ImGui::SameLine();

    ImGui::BeginChild("##historyPanel", ImVec2(sidepanel_width, 0), ImGuiChildFlags_None);
    {
        for (u32 i = 0; i < activity_count; i++)
        {
            activity ac = activity_buffer[i];

            char time_buffer[26];
            struct tm* tm_info;
            tm_info = localtime(&ac.timestamp);
            strftime(time_buffer, 26, "%d/%m/%Y %H:%M", tm_info);

            ImGui::Text(time_buffer);

            ImGui::PushFont(ui::fontBold);
            ImGui::Text(ac.user_name);
            ImGui::PopFont();
            ImGui::SameLine();
            
            ImGui::TextWrapped("%s", locale::get(ac.message));
            ImGui::Spacing();
        }
    }

    ImGui::EndChild();
}

static void draw_expense_update()
{
    if (ImGui::Button(locale::get("form.cancel"), true, false)) {
        current_view_state = ui::view_state::VIEW_EXISTING;
    }

    { // Save button
        bool can_save = administration::invoice_is_valid(&active_invoice) == A_ERR_SUCCESS;
        if (!can_save) ImGui::BeginDisabled();  
        ImGui::SameLine();
        if (ImGui::Button(locale::get("form.save"), true)) {
            administration_writer::set_write_completed_event_callback(_reset_to_invoice_view);
            administration::invoice_update(&active_invoice);

            _reload_activities();
        } 
        if (!can_save) ImGui::EndDisabled();
    }

    ImGui::Spacing();
    ImGui::Separator(3.0f);
    ImGui::Spacing();
    
    float availableWidth = ImGui::GetContentRegionAvail().x;
    ImGui::BeginChild("##invoicePanel", ImVec2(availableWidth - sidepanel_width, 0), ImGuiChildFlags_None);
    draw_expense_form(&active_invoice);
    ImGui::EndChild();

    _draw_activity_sidepanel();
}

static void draw_expense_create()
{
    if (ImGui::Button(locale::get("form.back"), true, false)) {
        _reset_to_default_view();
    }

    { // Save button
        bool can_save = administration::invoice_is_valid(&active_invoice) == A_ERR_SUCCESS;
        if (!can_save) ImGui::BeginDisabled(); 
        ImGui::SameLine();
        if (ImGui::Button(locale::get("form.save"), true)) {
            administration_writer::set_write_completed_event_callback(_reset_to_invoice_view);
            administration::invoice_add(&active_invoice);

            _reload_activities();
        } 
        if (!can_save) ImGui::EndDisabled();
    }

    ImGui::Spacing();
    ImGui::Separator(3.0f);
    ImGui::Spacing();
    
    float availableWidth = ImGui::GetContentRegionAvail().x;
    ImGui::BeginChild("##invoicePanel", ImVec2(availableWidth - sidepanel_width, 0), ImGuiChildFlags_None);
    draw_expense_form(&active_invoice);
    ImGui::EndChild();
}

static void draw_expense_view()
{
    if (ImGui::Button(locale::get("form.back"), true, false)) {
        _reset_to_default_view();
    }

    ImGui::SameLine();

    if (ImGui::Button(locale::get("form.change"))) {
        _set_active_invoice(administration::invoice_create_copy(&active_invoice)); // We create a copy because of billing item list pointers.
        current_view_state = ui::view_state::EDIT_EXISTING;
    }

    ImGui::Spacing();
    ImGui::Separator(3.0f);
    ImGui::Spacing();

    float availableWidth = ImGui::GetContentRegionAvail().x;
    ImGui::BeginChild("##invoicePanel", ImVec2(availableWidth - sidepanel_width, 0), ImGuiChildFlags_None);
    draw_expense_form(&active_invoice, true);
    ImGui::EndChild();

    _draw_activity_sidepanel();
}

static void draw_import_request()
{
    assert(active_import_request);

    if (active_import_request->status == importer::status::IMPORT_DONE) {
        if (active_import_request->error == I_ERR_SUCCESS) {
            active_invoice = active_import_request->result;
            current_view_state = ui::view_state::CREATE;
            active_import_request = 0;
            return;
        }
        else {
            if (ImGui::Button(locale::get("form.back"))) {
                _reset_to_default_view();
                active_import_request = 0;
                return;
            }
        }
    }

    ImGui::PushFont(ui::fontBig);

    ImVec2 windowSize = ImGui::GetWindowSize();
    float radius = 60.0f;
    
    const char* text = importer::status_to_string(active_import_request->status);
    if (active_import_request->error != I_ERR_SUCCESS) text = importer::error_to_string(active_import_request->error);
    ImVec2 textSize = ImGui::CalcTextSize(text);
    ImGui::SetCursorPos(ImVec2((windowSize.x - textSize.x) * 0.5f,
                    (windowSize.y) * 0.5f - radius - 40.0f));
    ImGui::Text(text);

    if (active_import_request->error == I_ERR_SUCCESS) {
        ImGui::SetCursorPos(ImVec2((windowSize.x - radius*2) * 0.5f,
                        (windowSize.y - radius*2) * 0.5f));

        const ImVec4 col = ImGui::GetStyleColorVec4(ImGuiCol_ButtonHovered);
        const ImVec4 bg = ImGui::GetStyleColorVec4(ImGuiCol_Button);
        ImGui::LoadingIndicatorCircle(radius, bg, col, 10, 4.0f);
    }

    ImGui::PopFont();
}

void ui::draw_expenses()
{
    switch(current_view_state)
    {
        case ui::view_state::LIST_ALL: draw_expenses_list(); break;
        case ui::view_state::CREATE: draw_expense_create(); break;
        case ui::view_state::EDIT_EXISTING: draw_expense_update(); break;
        case ui::view_state::VIEW_EXISTING: draw_expense_view(); break;
        case ui::view_state::VIEW_IMPORT_REQUEST: draw_import_request(); break;
    }
}