/**
 * Copyright (c) 2025 Dominic Masters
 * 
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "console.h"
#include "assert/assert.h"
#include "util/memory.h"
#include "util/string.h"
#include "input/input.h"

#include "console/cmd/cmdquit.h"
#include "console/cmd/cmdecho.h"
#include "console/cmd/cmdset.h"
#include "console/cmd/cmdget.h"
#include "console/cmd/cmdexec.h"
#include "console/cmd/cmdbind.h"
#include "console/cmd/cmdtoggleconsole.h"
#include "console/cmd/cmdalias.h"
#include "console/cmd/cmdscene.h"

console_t CONSOLE;

void consoleInit() {
  memoryZero(&CONSOLE, sizeof(console_t));

  // Register the get and set command.
  CONSOLE.cmdGet = consoleRegCmd("get", cmdGet);
  CONSOLE.cmdSet = consoleRegCmd("set", cmdSet);
  consoleRegCmd("quit", cmdQuit);
  consoleRegCmd("echo", cmdEcho);
  consoleRegCmd("exec", cmdExec);
  consoleRegCmd("bind", cmdBind);
  consoleRegCmd("toggleconsole", cmdToggleConsole);
  consoleRegCmd("alias", cmdAlias);
  consoleRegCmd("scene", cmdScene);

  #if CONSOLE_POSIX
    threadInit(&CONSOLE.thread, consoleInputThread);
    threadMutexInit(&CONSOLE.execMutex);
    threadStartRequest(&CONSOLE.thread);
  #endif
}

consolecmd_t * consoleRegCmd(const char_t *name, consolecmdfunc_t function) {
  consolecmd_t *cmd = &CONSOLE.commands[CONSOLE.commandCount++];
  consoleCmdInit(cmd, name, function);
  return cmd;
}

consolevar_t * consoleRegVar(
  const char_t *name,
  const char_t *value,
  consolevarchanged_t event
) {
  consolevar_t *var;

  // Existing?
  var = consoleVarGet(name);
  if(var != NULL) return var;

  assertTrue(
    CONSOLE.variableCount < CONSOLE_VARIABLES_MAX,
    "Too many console variables registered."
  );

  // Create
  var = &CONSOLE.variables[CONSOLE.variableCount++];
  consoleVarInitListener(var, name, value, event);
  return var;
}

consolevar_t * consoleVarGet(const char_t *name) {
  assertNotNull(name, "name must not be NULL");
  for(uint32_t i = 0; i < CONSOLE.variableCount; i++) {
    consolevar_t *var = &CONSOLE.variables[i];
    if(stringCompare(var->name, name) == 0) return var;
  }
  return NULL;
}

void consolePrint(const char_t *message, ...) {
  char_t buffer[CONSOLE_LINE_MAX];

  va_list args;
  va_start(args, message);
  int32_t len = stringFormatVA(buffer, CONSOLE_LINE_MAX, message, args);
  va_end(args);

  // Move all lines back
  memoryMove(
    CONSOLE.line[0],
    CONSOLE.line[1],
    (CONSOLE_HISTORY_MAX - 1) * CONSOLE_LINE_MAX
  );

  // Copy the new line
  memoryCopy(
    CONSOLE.line[CONSOLE_HISTORY_MAX - 1],
    buffer,
    len + 1
  );
  printf("%s\n", buffer);
}

void consoleExec(const char_t *line) {
  #if CONSOLE_POSIX
    threadMutexLock(&CONSOLE.execMutex);
  #endif

  assertNotNull(line, "line must not be NULL");
  assertTrue(
    CONSOLE.execBufferCount < CONSOLE_EXEC_BUFFER_MAX,
    "Too many commands in the buffer."
  );

  char_t buffer[CONSOLE_LINE_MAX];
  size_t i = 0, j = 0;
  char_t c;
  consoleexecstate_t state = CONSOLE_EXEC_STATE_INITIAL;
  consolecmdexec_t *exec = NULL;

  while(state != CONSOLE_EXEC_STATE_FULLY_PARSED) {
    c = line[i];

    switch(state) {
      case CONSOLE_EXEC_STATE_INITIAL:
        assertTrue(j == 0, "Buffer not empty?");

        if(c == '\0') {
          state = CONSOLE_EXEC_STATE_FULLY_PARSED;
          break;
        }

        if(stringIsWhitespace(c) || c == ';') {
          i++;
          continue;
        }

        state = CONSOLE_EXEC_STATE_PARSE_CMD;
        break;

      case CONSOLE_EXEC_STATE_PARSE_CMD:
        if(stringIsWhitespace(c) || c == '\0' || c == ';') {
          state = CONSOLE_EXEC_STATE_CMD_PARSED;
          continue;
        }

        if(c == '"') {
          // Can't handle quotes within the command.
          consolePrint("Invalid command");
          while(c != '\0' && c != ';') c = line[++i];
          continue;
        }
        
        buffer[j++] = c;
        i++;

        if(j >= CONSOLE_LINE_MAX) {
          consolePrint("Command too long");
          state = CONSOLE_EXEC_STATE_FULLY_PARSED;
          continue;
        }
        break;

      case CONSOLE_EXEC_STATE_CMD_PARSED:
        if(j == 0) {
          state = CONSOLE_EXEC_STATE_INITIAL;
          continue;
        }

        // Create exec
        assertNull(exec, "Existing command parsing?");

        exec = &CONSOLE.execBuffer[CONSOLE.execBufferCount];
        memoryZero(exec, sizeof(consolecmdexec_t));

        buffer[j] = '\0';
        stringCopy(exec->command, buffer, CONSOLE_LINE_MAX);
        state = CONSOLE_EXEC_STATE_FIND_ARG;

        j = 0;// Free up buffer
        break;

      case CONSOLE_EXEC_STATE_FIND_ARG:
        if(c == '\0' || c == ';') {
          state = CONSOLE_EXEC_STATE_CMD_FINISHED;
          continue;
        }

        if(stringIsWhitespace(c)) {
          i++;
          continue;
        }

        if(c == '"') {
          state = CONSOLE_EXEC_STATE_PARSE_ARG_QUOTED;
          i++;
        } else {
          state = CONSOLE_EXEC_STATE_PARSE_ARG;
        }
        break;

      case CONSOLE_EXEC_STATE_PARSE_ARG:
        if(stringIsWhitespace(c) || c == '\0' || c == ';') {
          state = CONSOLE_EXEC_STATE_ARG_PARSED;
          continue;
        }

        buffer[j++] = c;
        i++;

        if(j >= CONSOLE_LINE_MAX) {
          consolePrint("Arg too long");
          state = CONSOLE_EXEC_STATE_FULLY_PARSED;
          continue;
        }
        break;

      case CONSOLE_EXEC_STATE_PARSE_ARG_QUOTED:
        if(c == '"') {
          state = CONSOLE_EXEC_STATE_ARG_PARSED;
          i++;
          continue;
        }

        if(c == '\0' || c == ';') {
          consolePrint("Unterminated quote");
          state = CONSOLE_EXEC_STATE_FULLY_PARSED;
          continue;
        }

        if(c == '\\') {
          c = line[++i];

          if(c == '\0' || c == ';') {
            consolePrint("Unterminated quote");
            state = CONSOLE_EXEC_STATE_FULLY_PARSED;
            continue;
          }
        }

        buffer[j++] = c;
        i++;

        if(j >= CONSOLE_LINE_MAX) {
          consolePrint("Arg too long");
          state = CONSOLE_EXEC_STATE_FULLY_PARSED;
          continue;
        }
        break;

      case CONSOLE_EXEC_STATE_ARG_PARSED:
        buffer[j] = '\0';
        stringCopy(exec->argv[exec->argc++], buffer, CONSOLE_LINE_MAX);
        state = CONSOLE_EXEC_STATE_FIND_ARG;
        j = 0;// Free up buffer
        break;

      case CONSOLE_EXEC_STATE_CMD_FINISHED:
        assertNotNull(exec, "No command found?");

        // Now, is there a command that matches?
        for(uint32_t k = 0; k < CONSOLE.commandCount; k++) {
          consolecmd_t *cmd = &CONSOLE.commands[k];
          if(stringCompare(cmd->name, exec->command) != 0) continue;
          exec->cmd = cmd;
          break;
        }

        if(exec->cmd == NULL) {
          // Command wasn't found, is there a variable that matches?
          for(uint32_t k = 0; k < CONSOLE.variableCount; k++) {
            consolevar_t *var = &CONSOLE.variables[k];
            if(stringCompare(var->name, exec->command) != 0) continue;

            // Matching variable found, is this a GET or a SET?
            if(exec->argc == 0) {
              exec->cmd = CONSOLE.cmdGet;
              stringCopy(exec->argv[0], exec->command, CONSOLE_LINE_MAX);
              exec->argc = 1;
            } else {
              exec->cmd = CONSOLE.cmdSet;
              stringCopy(exec->argv[1], exec->argv[0], CONSOLE_LINE_MAX);
              stringCopy(exec->argv[0], exec->command, CONSOLE_LINE_MAX);
              exec->argc = 2;
            }
            break;
          }

          // Variable not found, is there an alias that matches?
          bool_t aliasFound = false;
          for(uint32_t k = 0; k < CONSOLE.aliasCount; k++) {
            consolealias_t *alias = &CONSOLE.aliases[k];
            if(stringCompare(alias->alias, exec->command) != 0) continue;

            // Matching alias found, we unlock the mutex and recursively call
            // consoleExec to handle the alias command.
            #if CONSOLE_POSIX
              threadMutexUnlock(&CONSOLE.execMutex);
            #endif
            consoleExec(alias->command);
            #if CONSOLE_POSIX
              threadMutexLock(&CONSOLE.execMutex);
            #endif

            aliasFound = true;
            break;
          }

          if(!aliasFound && exec->cmd == NULL) {
            consolePrint("Command \"%s\" not found", exec->command);
            exec = NULL;
            state = CONSOLE_EXEC_STATE_INITIAL;
            break;
          }
        }

        // Prep for next command.
        exec = NULL;
        state = CONSOLE_EXEC_STATE_INITIAL;
        CONSOLE.execBufferCount++;
        break;

      default:
        assertUnreachable("Invalid state.");
        break;
    }
  }

  #if CONSOLE_POSIX
    threadMutexUnlock(&CONSOLE.execMutex);
  #endif
}

void consoleUpdate() {
  #if CONSOLE_POSIX
    threadMutexLock(&CONSOLE.execMutex);
  #endif

  // Toggle console
  // if(inputPressed(INPUT_ACTION_CONSOLE)) {
  //   CONSOLE.visible = !CONSOLE.visible;
  // }

  // Anything to exec?
  if(CONSOLE.execBufferCount == 0) {
    #if CONSOLE_POSIX
      threadMutexUnlock(&CONSOLE.execMutex);
    #endif
    return;
  }

  // Copy the exec buffer, this allows exec command to work
  consolecmdexec_t execBuffer[CONSOLE_EXEC_BUFFER_MAX];
  uint32_t execBufferCount = CONSOLE.execBufferCount;
  memoryCopy(
    execBuffer,
    CONSOLE.execBuffer,
    sizeof(consolecmdexec_t) * execBufferCount
  );

  // Clear the exec buffer and unlock so new commands can be added while we
  // process the current ones.
  CONSOLE.execBufferCount = 0;
  #if CONSOLE_POSIX
    threadMutexUnlock(&CONSOLE.execMutex);
  #endif

  // Exec pending buffer.
  for(uint32_t i = 0; i < execBufferCount; i++) {
    consolecmdexec_t *exec = &execBuffer[i];
    assertNotNull(exec->cmd, "Command execution has no command.");
    exec->cmd->function(exec);
  }
}

void consoleDispose(void) {
  #if CONSOLE_POSIX
    threadStop(&CONSOLE.thread);
    threadMutexDispose(&CONSOLE.execMutex);
  #endif
}

#if CONSOLE_POSIX
  void consoleInputThread(thread_t *thread) {
    assertNotNull(thread, "Thread cannot be NULL.");

    char_t line[CONSOLE_LINE_MAX];
    size_t cap = 0;

    struct pollfd pfd = {
      .fd = STDIN_FILENO,
      .events = POLLIN
    };

    while(!threadShouldStop(thread) && ENGINE.running) {
      int32_t rc = poll(&pfd, 1, CONSOLE_POSIX_POLL_RATE);

      if(rc == 0) continue;
      if(rc < 0) {
        if(errno == EINTR) continue; // Interrupted by signal, retry
        assertUnreachable("poll() failed with unexpected error.");
      }

      // Check for errors or input
      if (pfd.revents & (POLLERR | POLLHUP | POLLNVAL)) break;
      if (!(pfd.revents & POLLIN)) {
        pfd.revents = 0;
        continue;
      }
      
      // Read a line from stdin
      if(!fgets(line, CONSOLE_LINE_MAX, stdin)) {
        if (feof(stdin)) break;
        clearerr(stdin);
        continue;
      }

      // Did we read a full line or did it get truncated?
      size_t len = strlen(line);
      int32_t fullLine = len > 0 && line[len - 1] == '\n';

      // Strip trailing newline/CR
      while(len && (line[len - 1] == '\n' || line[len - 1] == '\r')) {
        line[--len] = '\0';
      }

      if(len > 0) consoleExec(line);

      pfd.revents = 0;
    }
  }
#endif