#include "package_db.h"
#include "util.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <errno.h>

#define PKG_INFO_CMD "./scripts/get_pkg_attrs.sh"

// note: fixed location of package database for now
const char pkg_db[] = "./var/snag/packages";
const size_t pkg_db_len = sizeof(pkg_db) - 1;

bool load_package_info(char* pkgid, package_info_t* info) {

    memset(info, 0, sizeof(*info));
    size_t pkgid_len = strlen(pkgid);

	// construct package description directory path and ensure it exists
    // pkg_dir = "pkg_db/pkgid"
	size_t pkg_dir_len = pkg_db_len + pkgid_len + 1;
	char* pkg_dir = emalloc(pkg_dir_len + 1, "pkg_dir");
	{
		memcpy(pkg_dir, pkg_db, pkg_db_len);
		pkg_dir[pkg_db_len] = '/';
		memcpy(pkg_dir + pkg_db_len + 1, pkgid, pkgid_len);
		pkg_dir[pkg_dir_len] = '\0';
		if (access(pkg_dir, F_OK) != 0) {
			print("Package '%s' not found\n", pkgid);
			free(pkg_dir);
			return false;
		}
	}

	// construct package description script path and ensure it exists
	// script_path = "pkg_dir/pkgid.sh"
	size_t script_path_len = pkg_dir_len + pkgid_len + 4;
	info->script_path = emalloc(script_path_len + 1, "info->script_path");
	{
		memcpy(info->script_path, pkg_dir, pkg_dir_len);
		info->script_path[pkg_dir_len] = '/';
		memcpy(&info->script_path[pkg_dir_len + 1], pkgid, pkgid_len);
		memcpy(&info->script_path[script_path_len - 3], ".sh", 3);
		info->script_path[script_path_len] = '\0';
		free(pkg_dir);
		if (access(info->script_path, F_OK) != 0) {
			print("Package '%s' broken, doesn't have description script\n", pkgid);
			free(info->script_path);
			return false;
		}
	}

	// PIPE and FORK to run pkg attrs script
    int pipefds[2] = {0};
    if (pipe(pipefds) < 0) die("failed to pipe: %s", strerror(errno));
    pid_t pid = fork();
    if (pid < 0) die("failed to fork: %s", strerror(errno));

    if (pid == 0) {
		// child proc
		// connect my stdout to the pipe
        close(pipefds[0]);
        dup2(pipefds[1], STDOUT_FILENO);
        close(pipefds[1]);
		// exec into get attr script
        char* argv[] = { PKG_INFO_CMD, info->script_path, NULL };
        char* envp[] = { NULL };
        execve(PKG_INFO_CMD, argv, envp);
		// what are you still doing here?
		die("CHILD - execve to %s failed: %s", PKG_INFO_CMD, strerror(errno));
    } else {
		// parent proc, close write end of pipe
		close(pipefds[1]);
	}

	// wait for child to finish
    int wstatus;
    if (waitpid(pid, &wstatus, 0) < 0) die("waitpid failed: %s", strerror(errno));
	if (WEXITSTATUS(wstatus) != 0) die("the child failed to execute get_pkg_attr script: %d", WEXITSTATUS(wstatus));

	// read all bytes from pipe into attr buffer
    ssize_t bytes_read = read(pipefds[0], info->attrs.buffer, sizeof(info->attrs.buffer));
    if (bytes_read < 0) die("failed to read from pipe: %s", strerror(errno));
	close(pipefds[0]);

	// read attributes from attr buffer
	// attribute format: type (char), data value (null terminated str)
	// todo(jqj): switch over to dynamically allocated buffer
    for (int i = 0; i < bytes_read;) {
        char atype = info->attrs.buffer[i];
        i++;
        switch (atype) {
        case 'i':
            info->attrs.id = &info->attrs.buffer[i]; break;
        case 'n':
            info->attrs.name = &info->attrs.buffer[i]; break;
        case 'd':
            info->attrs.desc = &info->attrs.buffer[i]; break;
		case 'w':
			info->attrs.webpage = &info->attrs.buffer[i]; break;
		case 'l':
			info->attrs.license = &info->attrs.buffer[i]; break;
		case 'v':
			info->attrs.version = &info->attrs.buffer[i]; break;
		case 'u':
			info->attrs.source_url = &info->attrs.buffer[i]; break;
		case 'c':
			info->attrs.source_checksum = &info->attrs.buffer[i]; break;
        }
        for(;info->attrs.buffer[i] && i < bytes_read; i++);
        i++;
    }

	return true;
}