/**
 * @file output.c
 * @brief Screen rendering and output module for the Beluga text editor
 * @details Handles all screen updates, cursor positioning, status bar
 * rendering, and display synchronization using ANSI escape sequences
 */

#include "../include/output.h"
#include "../include/append_buffer.h"
#include "../include/buffer.h"
#include "../include/editor_op.h"
#include "../include/data.h"
#include "../include/define.h"
#include "../include/row_op.h"
#include "../include/split_screen.h"
#include "../include/syntax_highlighter.h"
#include "../include/terminal.h"
#include "../include/lsp_ui.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "include/completion.h"
#include "include/utils.h"

/**
 * @brief Renders a single pane with its buffer content
 */
static void editorDrawPane(struct abuf* ab, EditorPane* pane)
{
    int file_row;
    char pos_buf[32];
    int pos_len;
    int byte_len_to_print;
    int bytes_to_print;
    char* highlighted;

    if (pane == NULL || pane->buffer_id < 0)
        return;

    const struct buffer_t* buf = bufferFindById(pane->buffer_id);
    if (buf == NULL)
        return;

    // Draw all pane
    for (int y = 0; y < pane->height; y++)
    {
        file_row = y + pane->y_offset;

        // Set cursor at start of pane row
        pos_len = snprintf(pos_buf, sizeof(pos_buf), "\x1b[%d;%dH",
                           pane->origin_y + y + 1, pane->origin_x + 1);
        abAppend(ab, pos_buf, pos_len);

        // Apply background color (6 bytes for RGB format)
        abAppend(ab, E.theme.BACKGROUND_COLOR, (int)strlen(E.theme.BACKGROUND_COLOR));


        // pane line is out of buffer
        if (file_row >= buf->numrows)
        {
            // Empty line - show tilde

            abAppend(ab, "~", 1);
            for (int i = 0;
                 i < pane->width - 1;
                 ++i)
            {
                abAppend(ab, " ", 1);
            }
        }
        else
        {
            if (E.constantes.LSP) {
                    lspUiDrawGutter(ab, &E.lsp_diagnostics, pane->buffer_id, file_row);
            }


            if (buf->filename[strlen(buf->filename) - 1] == 'c' || buf->filename[strlen(buf->filename) - 1] == 'h')
            {
                // Render line with syntax highlighting, constrain to pane width
                highlighted = highlight_line(
                    &buf->row[file_row].chars[pane->x_offset], &byte_len_to_print);

                // Print only up to pane width
                abAppend(ab, highlighted, byte_len_to_print);
                bFree(highlighted);
            }
            else
            {
                // Render basic line
                bytes_to_print =
                    buf->row[file_row].size - pane->x_offset < pane->width
                        ? buf->row[file_row].size - pane->x_offset
                        : pane->width;
                abAppend(ab, &buf->row[file_row].chars[pane->x_offset], bytes_to_print);
            }
            // Fill remaining space with background color to pane width
            for (int i = 0;
                 i < pane->width - editorRowCharCount(&buf->row[file_row], pane->width) + pane->x_offset;
                 ++i)
            {
                abAppend(ab, " ", 1);
            }
        }
    }
}

/**
 * @brief Renders all panes based on current split configuration
 */
static void editorDrawAllPanes(struct abuf* ab)
{
    const ScreenLayout* layout = splitScreenGetLayout();

    if (layout->num_panes == 1)
    {
        // Single pane fullscreen
        editorDrawPane(ab, &layout->panes[0]);
    }
    else if (layout->num_panes == 2)
    {
        // Draw both panes
        for (int i = 0; i < 2; i++)
        {
            editorDrawPane(ab, &layout->panes[i]);

            // Draw pane border/divider if not the last pane
            if (layout->mode == SPLIT_VERTICAL && i == 0)
            {
                // Draw vertical divider
                int divider_col = layout->panes[0].width;
                for (int y = 0; y < layout->panes[0].height; y++)
                {
                    char pos_buf[32];
                    snprintf(pos_buf, sizeof(pos_buf), "\x1b[%d;%dH", y + 1, divider_col);
                    abAppend(ab, pos_buf, (int)strlen(pos_buf));
                    abAppend(ab, "\x1b[1m|\x1b[0m", 9); // Bold pipe divider
                }
            }
            else if (layout->mode == SPLIT_HORIZONTAL && i == 0)
            {
                // Draw horizontal divider
                int divider_row = layout->panes[0].height;
                char pos_buf[32];
                snprintf(pos_buf, sizeof(pos_buf), "\x1b[%d;%dH", divider_row + 1, 1);
                abAppend(ab, pos_buf, (int)strlen(pos_buf));
                for (int x = 0; x < E.screencols; x++)
                {
                    abAppend(ab, "\x1b[1m-\x1b[0m", 9); // Bold dash divider
                }
            }
        }
    }
}

/**
 * @brief Updates scroll offsets to keep cursor visible on screen
 * @details Adjusts E.row_offset and E.col_offset to ensure the cursor remains
 * within the visible viewport. Also updates E.rx (rendered x-coordinate).
 * @note Updates global editor state E
 * @see editorRowCxToRx()
 */
void editorScroll()
{
    EditorPane* active = splitScreenGetActivePane();
    struct buffer_t* buf = bufferFindById(active->buffer_id);
    int rel_x, rel_y;

    // compute relative coordinates
    rel_x = editorRowCharCount(&buf->row[buf->y], buf->x);
    appDebug("counting %d\n", rel_x);
    rel_y = buf->y;

    appDebug("%d %d / %d %d\n", active->cursor_x, active->x_offset,
             active->cursor_y, active->y_offset);

    while (rel_x != active->cursor_x + active->x_offset ||
        rel_y != active->cursor_y + active->y_offset)
    {
        if (rel_x < active->cursor_x + active->x_offset)
        {
            // LEFT
            if (active->cursor_x == 0 && active->x_offset)
            {
                active->x_offset--;
            }
            else
            {
                active->cursor_x--;
            }
        }
        else
        {
            // RIGHT
            if (rel_x > active->cursor_x + active->x_offset)
            {
                if (active->cursor_x == active->width - 1)
                {
                    active->x_offset++;
                }
                else
                {
                    active->cursor_x++;
                }
            }
        }

        if (rel_y < active->cursor_y + active->y_offset)
        {
            if (active->cursor_y == 0 && active->y_offset)
            {
                active->y_offset--;
            }
            else
            {
                active->cursor_y--;
            }
        }

        if (rel_y > active->cursor_y + active->y_offset)
        {
            if (active->cursor_y == active->height - 1)
            {
                active->y_offset++;
            }
            else
            {
                active->cursor_y++;
            }
        }
    }
}

char* basename(char* path)
{
    int len = (int)strlen(path);


    for (int i = len - 1; i > 0; i--)
    {
        if (path[i] == '/')
        {
            path = path + i + 1;
            break;
        }
    }
    return path;
}

/**
 * @brief Renders the status bar at the bottom of the screen
 * @details Displays filename, line count, dirty flag, and current cursor
 * position in an inverted color bar. Right-aligns the cursor position
 * indicator.
 * @param ab Pointer to append buffer structure for accumulating output
 * @note Uses ANSI escape codes for color inversion
 */
void editorDrawStatusBar(struct abuf* ab)
{
    // TO MODIFY
    int len, render_len;
    char status[E.screencols], render_status[E.screencols * 4];
    EditorPane* active = splitScreenGetActivePane();
    struct buffer_t* buf = bufferFindById(active->buffer_id);

    abAppend(ab, "\x1b[7m", 4); // inverting colors

    const char* mode_str = "";
    ScreenLayout* layout = splitScreenGetLayout();
    if (layout->mode == SPLIT_VERTICAL)
        mode_str = " [V-SPLIT]";
    else if (layout->mode == SPLIT_HORIZONTAL)
        mode_str = " [H-SPLIT]";

    // Build buffer status showing all buffers with dirty indicators
    char buf_status[1024] = "";
    int offset = 0;
    for (int i = 0; i < E.number_of_buffer; i++)
    {
        struct buffer_t* b = &E.buffers[i];
        char marker = (b->buffer_id == active->buffer_id) ? '>' : ' ';
        char dirty_marker = b->dirty ? '*' : ' ';
        offset += snprintf(&buf_status[offset], sizeof(buf_status) - offset,
                           "%c%d:%s%c ", marker, b->buffer_id,
                           b->filename ? basename(b->filename) : "[No Name]", dirty_marker);
    }

    len = snprintf(status, sizeof(status), "%s%s", buf_status, mode_str);

    render_len = snprintf(render_status, sizeof(render_status), "%d/%d",
                          active->cursor_y + 1, buf->numrows);

    if (len > E.screencols)
    {
        len = E.screencols;
    }

    abAppend(ab, status, len);
    while (len < E.screencols)
    {
        if (E.screencols - len == render_len + 1)
        {
            abAppend(ab, render_status, render_len);
            break;
        }
        abAppend(ab, " ", 1);
        ++len;
    }

    abAppend(ab, "\x1b[m", 3); // normal text mode
    abAppend(ab, "\r\n", 2);
}

/**
 * @brief Renders the message bar below the status bar
 * @details Displays temporary status messages for a limited time (5 seconds).
 * Only displays message if within time window and within screen width.
 * @param ab Pointer to append buffer structure for accumulating output
 * @note Messages are set by editorSetStatusMessage()
 */
void editorDrawMessageBar(struct abuf* ab)
{
    int msg_len = (int)strlen(E.status_msg);
    abAppend(ab, ERASE_END_LINE, 3);
    if (msg_len > E.screencols)
    {
        msg_len = E.screencols;
    }
    if (msg_len && time(NULL) - E.status_msg_time < 5)
    {
        abAppend(ab, E.status_msg, msg_len);
    }
}

/**
 * @brief Performs complete screen refresh and buffer synchronization
 * @details Clears screen, redraws all visible content (rows, status bar,
 * message bar), positions cursor, and writes accumulated buffer to stdout. This
 * is the main rendering function called each frame.
 * @note Updates global editor state E (via editorScroll())
 * @see editorDrawRows()
 * @see editorDrawStatusBar()
 * @see editorDrawMessageBar()
 */

void editorRefreshScreen()
{
    struct abuf ab = ABUF_INIT;
    char buf[32];

    abAppend(&ab, HIDE_CURSOR, 6);
    abAppend(&ab, CURSOR_TOP_LEFT, 3);
    abAppend(&ab, E.theme.BACKGROUND_COLOR,
             (int)strlen(E.theme.BACKGROUND_COLOR));

    editorScroll();


    EditorPane* active = splitScreenGetActivePane();
    struct buffer_t* buffer = bufferFindById(active->buffer_id);

    editorDrawAllPanes(&ab);
    if (E.constantes.LSP) {

        // ── LSP: draw completion popup every frame while visible ──────────────────
        appDebug("[REFRESH] lsp_completion.visible=%d\n",
                E.lsp_completion.visible);
        while (E.lsp_client->completion_requested && !E.lsp_client->completion_just_arrived);
        // reset flags
        E.lsp_client->completion_just_arrived = 0;
        E.lsp_client->completion_requested = 0;

        // ── LSP: diagnostic for current line in status bar ────────────────────────
        const char* diag = lspUiDiagnosticAtCursor(
            &E.lsp_diagnostics,
            active->buffer_id,
            buffer->y);
        if (diag) {
            char single_line[512];
            int i = 0;

            // Copy until newline, \0, or screen width
            while (diag[i] && diag[i] != '\n' && i < E.screencols - 4)
            {
                single_line[i] = diag[i];
                i++;
            }

            // If message was truncated, add ellipsis
            if (diag[i] != '\0' && diag[i] != '\n')
            {
                single_line[i++] = '.';
                single_line[i++] = '.';
                single_line[i++] = '.';
            }
            single_line[i] = '\0';
            editorSetStatusMessage("● %s", single_line);
        }

    }
    editorDrawStatusBar(&ab);
    editorDrawMessageBar(&ab);
    if (E.constantes.LSP && (E.lsp_client && E.lsp_client->state == LSP_READY))
    {
        lspUiDrawCompletion(&ab, &E.lsp_completion);
    }


    // ── Position cursor (account for gutter width) ────────────────────────────
    snprintf(buf, sizeof(buf), "\x1b[%d;%dH",
             active->cursor_y + active->origin_y + 1,
             active->cursor_x + active->origin_x + 1 + (E.constantes.LSP ? GUTTER_WIDTH : 0));
    abAppend(&ab, buf, (int)strlen(buf));

    abAppend(&ab, SHOW_CURSOR, 6);
    write(STDOUT_FILENO, ab.b, ab.len);
    abFree(&ab);
}