root/tasks/edit.c

DEFINITIONS

1. ReadFile
2. PrintStatusLine
3. RedrawScreen
4. main

/*
 * edit.c
 *
 *  Created on: Mar 26, 2012
 *      Author: ian
 */
#include "lib.h"
#include "syscalls.h"

#define ctrl(x) x - 0x40
#define ESC 27
#define CLRBUFF for (count = 0; count < 80; count++) currentLineBuffer[count] = 0
#define Overwrite   0
#define Insert      1
#define WINDOWSIZE  20

struct line
{
    struct line *next;
    struct line *prev;
    int lineno;
    unsigned char *line;
};

struct line *lines;
struct line *windowStart;
int line;
int column;
char mode;
int count;

void ReadFile(FD file)
{
    struct line *firstline = lines;
    struct line *currline;

    // First read the whole file into a buffer
    struct FileInfo info;
    fstat(file, &info);
    int filesize = info.Length;
    unsigned char *buffer = malloc(filesize);
    read(file, buffer, filesize);

    // Parse the buffer into separate lines
    lines = malloc(sizeof(struct line));
    lines->next = 0;
    lines->prev = 0;
    lines->lineno = 0;
    currline = lines;

    int i;
    while (filesize)
    {
        while (buffer[i] != 0x0a && i < filesize)
            i++;
        buffer[i] = 0;
        currline->line = malloc(i + 1);
        strcpy(currline->line, buffer);
        buffer = buffer + i + 1;
        filesize -= i + 1;
        if (filesize)
        {
            i = 0;
            currline->next = malloc(sizeof(struct line));
            currline->next->prev = currline;
            currline = currline->next;
        }
    }
}

void PrintStatusLine()
{
    if (mode == Insert)
    {
        printf(
                "%c[24;1H%c[?5h^Q Quit  ^I Insert toggle  Insert on                                          ",
                ESC, ESC);
        printf("%c[%d;%dH%c[?5l", ESC, line, column, ESC);
    }
    else
    {
        // Print status line
        printf(
                "%c[24;1H%c[?5h^Q Quit  ^I Insert toggle  Insert off                                          ",
                ESC, ESC);
        printf("%c[%d;%dH%c[?5l", ESC, line, column, ESC);

    }
}

void RedrawScreen()
{
    struct line *tempcurrline = lines;
    printf("%c[2J", ESC);
    tempcurrline = windowStart;
    if (!windowStart) return;
    for (count = 0; count <= WINDOWSIZE; count++)
    {
        if (tempcurrline->line)
            printf("%s\n", tempcurrline->line);
        if (!tempcurrline->next)
            break;
        tempcurrline = tempcurrline->next;
    }
    PrintStatusLine();
}

int main(int argc, char **argv)
{
    lines = 0;

    FD file;
    line = 0;
    column = 0;
    struct line *currline;
    char currentLineBuffer[80];
    int count;
    mode = Insert;

    // Clear the screen
    printf("%c[2J", ESC);

    if (argc == 2)
    {
        file = open(argv[1]);
        if (file != -1)
        {
            ReadFile(file);
            windowStart = lines;
            RedrawScreen();
        }
        else
        {
            lines = malloc(sizeof(struct line));
            lines->next = 0;
            lines->prev = 0;
            lines->lineno = 0;
            lines->line = malloc(80);
        }
        currline = lines;
    }
    int done = 0;
    PrintStatusLine();
    CLRBUFF;
    char c;
    if (currline->line)
        strcpy(currentLineBuffer, currline->line);

    while (!done)
    {
        c = getchar();
        switch (c)
        {
        case ctrl('Q'):
            done = 1;
            break;
        case ctrl('I'):
            if (mode == Insert)
                mode = Overwrite;
            else
                mode = Insert;
            PrintStatusLine();
            break;
        case ctrl('M'): // Return
            ;
            int linelength = strlen(currentLineBuffer);
            currentLineBuffer[column] = 0;
            // Copy the line up to cursor back to currline->line
            free(currline->line);
            currline->line = malloc(strlen(currentLineBuffer) + 1);
            currentLineBuffer[column] = 0;
            strcpy(currline->line, currentLineBuffer);
            // Create a new struct line for the new line
            struct line *temp = malloc(sizeof(struct line));
            // Link it into the list
            temp->next = currline->next;
            currline->next = temp;
            if (temp->next)
                temp->next->prev = temp;
            temp->prev = currline;
            if (column < linelength)
            {
                temp->line = malloc(strlen(currentLineBuffer + column) + 1);
                strcpy(temp->line, currentLineBuffer + column + 1);
            }
            else
            {
                temp->line = malloc(1);
                temp->line[0] = 0;
            }
            CLRBUFF;
            strcpy(currentLineBuffer, temp->line);
            // Reset all the counters and reposition the cursor
            column = 0;
            line++;
            currline = currline->next;
            RedrawScreen(windowStart);
            break;
        case ctrl('U'): // Up Arrow
            if (currline->prev)
            {
                line--;
                free(currline->line);
                currline->line = malloc(strlen(currentLineBuffer) + 1);
                strcpy(currline->line, currentLineBuffer);
                currline = currline->prev;
                CLRBUFF;
                if (currline->line)
                    strcpy(currentLineBuffer, currline->line);
                if (column > strlen(currentLineBuffer))
                    column = strlen(currentLineBuffer);
                printf("%c[%d;%dH", ESC, line, column);
                if (line < 0)
                {
                    windowStart = windowStart->prev;
                    line++;
                    RedrawScreen();
                }
            }
            break;
        case ctrl('D'): // Down Arrow
            if (currline->next)
                {
                line++;
                free(currline->line);
                currline->line = malloc(strlen(currentLineBuffer) + 1);
                strcpy(currline->line, currentLineBuffer);
                currline = currline->next;
                CLRBUFF;
                if (currline->line)
                    strcpy(currentLineBuffer, currline->line);
                if (column > strlen(currentLineBuffer))
                    column = strlen(currentLineBuffer);
                printf("%c[%d;%dH", ESC, line, column);
                if (line > WINDOWSIZE)
                {
                    windowStart = windowStart->next;
                    line--;
                    RedrawScreen();
                }
            }
            break;
        case ctrl('L'): // Left Arrow
            if (column)
            {
                printf("%c[1D", ESC);
                column--;
            }
            break;
        case ctrl('R'): // Right Arrow
            if (column < 80 && column < strlen(currentLineBuffer))
            {
                column++;
                printf("%c[1C", ESC);
            }
            break;
        case 8: // BackSpace
            if (column)
            {
                int i;
                for (i = column; i < 80; i++)
                    currentLineBuffer[i - 1] = currentLineBuffer[i];
                column--;
                printf("%c[1D", ESC);
                printf("%s", currentLineBuffer + column);
                printf("%c[%d;%dH", ESC, line, column);
            }
            break;
        default:
            if (mode == Insert)
            {
                int i;
                for (i = 80; i > column; i--)
                    currentLineBuffer[i] = currentLineBuffer[i - 1];
            }
            currentLineBuffer[column] = c;
            printf("%s", currentLineBuffer + column);
            if (column < 80)
                column++;
            printf("%c[%d;%dH", ESC, line, column);
            break;
        }
    }
    free(currline->line);
    currline->line = malloc(strlen(currentLineBuffer) + 1);
    strcpy(currline->line, currentLineBuffer);

// Clear the screen
    printf("%c[2J", ESC);
    if (file != -1)
    {
        close(file);
        unlink(argv[1]);
    }
    file = creat(argv[1]);
    currline = lines;
    if (file)
    {
        while (currline)
        {
            if (currline->line)
            {
                write(file, currline->line, strlen(currline->line));
                write(file, "\n", 1);
            }
            currline = currline->next;
        }
        close(file);
    }
    free(lines->line);
    free(lines);
    exit();
    return 0;
}