#include "cst_keymap.h"

#include "cJSON.h"
#include "cst_util.h"
#include "os_compat.h"

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static const cst_key_action_info_t INFO[CST_KA_COUNT] = {
    [CST_KA_PALETTE] = {"palette", "General", "command palette", NULL},
    [CST_KA_KEYS] = {"keys", "General", "keyboard shortcuts", "/keys"},
    [CST_KA_MODE] = {"mode", "General", "switch Build / Plan mode", NULL},
    [CST_KA_APPROVAL] = {"approval", "General", "cycle approval ask/auto/yolo",
                         NULL},
    [CST_KA_NEWLINE] = {"newline", "General", "insert a newline", NULL},
    [CST_KA_REDRAW] = {"redraw", "General", "redraw the screen", NULL},
    [CST_KA_QUIT] = {"quit", "General", "quit", "/quit"},
    [CST_KA_TOGGLE_TOOL] = {"toggle_tool", "View",
                            "expand/collapse the last tool output", NULL},
    [CST_KA_TOGGLE_THOUGHT] = {"toggle_thought", "View",
                               "expand/collapse the last thought", NULL},
    [CST_KA_THINKING_ALL] = {"thinking", "View",
                             "show/hide all thoughts by default", "/thinking"},
    [CST_KA_DETAILS] = {"details", "View", "expand/collapse all tool output",
                        "/details"},
    [CST_KA_TODO] = {"todo", "View", "show/hide the task panel", NULL},
    [CST_KA_SIDEBAR] = {"sidebar", "View", "show/hide the sidebar",
                        "/sidebar"},
    [CST_KA_SCROLL_UP] = {"scroll_up", "View", "scroll up half a page", NULL},
    [CST_KA_SCROLL_DOWN] = {"scroll_down", "View", "scroll down half a page",
                            NULL},
    [CST_KA_LINE_UP] = {"line_up", "View", "scroll up one line", NULL},
    [CST_KA_LINE_DOWN] = {"line_down", "View", "scroll down one line", NULL},
    [CST_KA_TOP] = {"top", "View", "jump to the first message", NULL},
    [CST_KA_BOTTOM] = {"bottom", "View", "jump to the latest message", NULL},
    [CST_KA_NEW_SESSION] = {"new_session", "Session", "start a new session",
                            "/new"},
    [CST_KA_SESSIONS] = {"sessions", "Session", "pick a session", "/session"},
    [CST_KA_UNDO] = {"undo", "Session", "revert the last turn's file changes",
                     "/undo"},
    [CST_KA_RETRY] = {"retry", "Session", "drop the last reply and ask again",
                      "/retry"},
    [CST_KA_COMPACT] = {"compact", "Session", "summarize the context",
                        "/compact"},
    [CST_KA_COPY] = {"copy", "Session", "copy the last reply", "/copy"},
    [CST_KA_EXPORT] = {"export", "Session", "export the transcript",
                       "/export"},
    [CST_KA_PASTE_IMAGE] = {"paste_image", "Session",
                            "attach the clipboard image", "/attach paste"},
    [CST_KA_MODEL] = {"model", "Model", "pick the model", "/model"},
    [CST_KA_PROVIDER] = {"provider", "Model", "switch provider", "/provider"},
    [CST_KA_EFFORT] = {"effort", "Model", "reasoning effort", "/effort"},
    [CST_KA_AGENTS] = {"agents", "Agents", "sub-agents and roles", "/agents"},
    [CST_KA_SKILLS] = {"skills", "Agents", "skills", "/skills"},
    [CST_KA_PLUGINS] = {"plugins", "Agents", "plugins and MCP servers",
                        "/plugins"},
};

static const struct {
  int action;
  const char *keys;
} DEFAULTS[] = {
    {CST_KA_PALETTE, "ctrl+p"},
    {CST_KA_KEYS, "<leader> h"},
    {CST_KA_KEYS, "f1"},
    {CST_KA_MODE, "tab"},
    {CST_KA_APPROVAL, "shift+tab"},
    {CST_KA_NEWLINE, "ctrl+n"},
    {CST_KA_NEWLINE, "alt+enter"},
    {CST_KA_REDRAW, "ctrl+l"},
    {CST_KA_QUIT, "<leader> q"},
    {CST_KA_TOGGLE_TOOL, "ctrl+o"},
    {CST_KA_TOGGLE_THOUGHT, "ctrl+r"},
    {CST_KA_THINKING_ALL, "<leader> t"},
    {CST_KA_DETAILS, "<leader> d"},
    {CST_KA_TODO, "ctrl+t"},
    {CST_KA_SIDEBAR, "<leader> s"},
    {CST_KA_SCROLL_UP, "pgup"},
    {CST_KA_SCROLL_DOWN, "pgdn"},
    {CST_KA_LINE_UP, "alt+up"},
    {CST_KA_LINE_DOWN, "alt+down"},
    {CST_KA_TOP, "ctrl+home"},
    {CST_KA_BOTTOM, "ctrl+end"},
    {CST_KA_NEW_SESSION, "<leader> n"},
    {CST_KA_SESSIONS, "<leader> l"},
    {CST_KA_UNDO, "<leader> u"},
    {CST_KA_RETRY, "<leader> r"},
    {CST_KA_COMPACT, "<leader> c"},
    {CST_KA_COPY, "<leader> y"},
    {CST_KA_EXPORT, "<leader> x"},
    {CST_KA_PASTE_IMAGE, "ctrl+v"},
    {CST_KA_MODEL, "<leader> m"},
    {CST_KA_PROVIDER, "<leader> p"},
    {CST_KA_EFFORT, "<leader> e"},
    {CST_KA_AGENTS, "<leader> a"},
    {CST_KA_SKILLS, "<leader> k"},
    {CST_KA_PLUGINS, "<leader> g"},
};

static const struct {
  const char *name;
  int code;
} NAMED[] = {
    {"tab", 9},
    {"enter", 13},
    {"return", 13},
    {"esc", 27},
    {"escape", 27},
    {"space", ' '},
    {"backspace", 127},
    {"up", CST_K_UP},
    {"down", CST_K_DOWN},
    {"left", CST_K_LEFT},
    {"right", CST_K_RIGHT},
    {"home", CST_K_HOME},
    {"end", CST_K_END},
    {"pgup", CST_K_PGUP},
    {"pageup", CST_K_PGUP},
    {"pgdn", CST_K_PGDN},
    {"pagedown", CST_K_PGDN},
    {"delete", CST_K_DEL},
    {"del", CST_K_DEL},
    {"insert", CST_K_INS},
};

const cst_key_action_info_t *cst_key_action_info(int action) {
  return action > CST_KA_NONE && action < CST_KA_COUNT ? &INFO[action] : NULL;
}

int cst_key_action_find(const char *name) {
  for (int i = 1; name && i < CST_KA_COUNT; i++)
    if (INFO[i].name && strcmp(INFO[i].name, name) == 0)
      return i;
  return CST_KA_NONE;
}

static int ieq(const char *a, const char *b, size_t n) {
  if (strlen(b) != n)
    return 0;
  for (size_t i = 0; i < n; i++)
    if (tolower((unsigned char)a[i]) != b[i])
      return 0;
  return 1;
}

/* Decode one UTF-8 code point; returns bytes used (0 on error). */
static int utf8_one(const char *s, size_t n, int *cp) {
  const unsigned char *u = (const unsigned char *)s;
  if (n >= 1 && u[0] < 0x80) {
    *cp = u[0];
    return 1;
  }
  if (n >= 2 && (u[0] & 0xE0) == 0xC0) {
    *cp = ((u[0] & 0x1F) << 6) | (u[1] & 0x3F);
    return 2;
  }
  if (n >= 3 && (u[0] & 0xF0) == 0xE0) {
    *cp = ((u[0] & 0x0F) << 12) | ((u[1] & 0x3F) << 6) | (u[2] & 0x3F);
    return 3;
  }
  if (n >= 4 && (u[0] & 0xF8) == 0xF0) {
    *cp = ((u[0] & 0x07) << 18) | ((u[1] & 0x3F) << 12) |
          ((u[2] & 0x3F) << 6) | (u[3] & 0x3F);
    return 4;
  }
  return 0;
}

static int parse_key_n(const char *s, size_t n) {
  int ctrl = 0, alt = 0, shift = 0;
  for (;;) {
    const char *plus = memchr(s, '+', n);
    if (!plus || plus == s + n - 1)
      break;
    size_t m = (size_t)(plus - s);
    if (ieq(s, "ctrl", m) || ieq(s, "c", m))
      ctrl = 1;
    else if (ieq(s, "alt", m) || ieq(s, "meta", m) || ieq(s, "m", m))
      alt = 1;
    else if (ieq(s, "shift", m) || ieq(s, "s", m))
      shift = 1;
    else
      return -1;
    n -= m + 1;
    s = plus + 1;
  }
  if (n == 0)
    return -1;
  int code = -1;
  for (size_t i = 0; i < sizeof(NAMED) / sizeof(NAMED[0]); i++)
    if (ieq(s, NAMED[i].name, n))
      code = NAMED[i].code;
  if (code < 0 && (s[0] == 'f' || s[0] == 'F') && n >= 2 && n <= 3) {
    int f = atoi(s + 1);
    if (f >= 1 && f <= 12 && isdigit((unsigned char)s[1]))
      code = CST_K_F1 + f - 1;
  }
  if (code < 0) {
    int cp = 0;
    if (utf8_one(s, n, &cp) != (int)n)
      return -1;
    code = cp;
  }
  if (shift) {
    if (code == 9)
      code = CST_K_BTAB;
    else if (code < 128 && isalpha(code))
      code = toupper(code);
    else
      return -1;
  }
  if (ctrl) {
    if (code < 128 && isalpha(code))
      code = tolower(code) - 'a' + 1;
    else if (code == CST_K_HOME)
      code = CST_K_CTRL_HOME;
    else if (code == CST_K_END)
      code = CST_K_CTRL_END;
    else if (code == CST_K_UP)
      code = CST_K_CTRL_UP;
    else if (code == CST_K_DOWN)
      code = CST_K_CTRL_DOWN;
    else
      return -1;
  }
  if (alt) {
    if (code == CST_K_UP)
      return CST_K_ALT_UP;
    if (code == CST_K_DOWN)
      return CST_K_ALT_DOWN;
    code |= CST_KEY_ALT;
  }
  return code;
}

int cst_key_parse(const char *s) {
  if (!s)
    return -1;
  while (*s == ' ')
    s++;
  size_t n = strlen(s);
  while (n && s[n - 1] == ' ')
    n--;
  return parse_key_n(s, n);
}

const char *cst_key_name(int code, char *buf, size_t n) {
  const char *alt = (code & CST_KEY_ALT) ? "alt+" : "";
  int c = code & ~CST_KEY_ALT;
  static const char *const SPECIAL[] = {
      "up",        "down",     "left",      "right",     "home",
      "end",       "pgup",     "pgdn",      "shift+tab", "delete",
      "insert",    "ctrl+home", "ctrl+end", "ctrl+up",   "ctrl+down",
      "alt+up",    "alt+down"};
  if (c == 9)
    snprintf(buf, n, "%stab", alt);
  else if (c == 13 || c == 10)
    snprintf(buf, n, "%senter", alt);
  else if (c == 27)
    snprintf(buf, n, "%sesc", alt);
  else if (c == ' ')
    snprintf(buf, n, "%sspace", alt);
  else if (c == 127 || c == 8)
    snprintf(buf, n, "%sbackspace", alt);
  else if (c >= 1 && c <= 26)
    snprintf(buf, n, "%sctrl+%c", alt, 'a' + c - 1);
  else if (c >= CST_K_F1 && c <= CST_K_LAST)
    snprintf(buf, n, "%sf%d", alt, c - CST_K_F1 + 1);
  else if (c >= CST_KEY_SPECIAL && c < CST_K_F1)
    snprintf(buf, n, "%s%s", alt, SPECIAL[c - CST_KEY_SPECIAL]);
  else if (c >= 'A' && c <= 'Z')
    snprintf(buf, n, "%sshift+%c", alt, c - 'A' + 'a');
  else if (c < 0x80)
    snprintf(buf, n, "%s%c", alt, c);
  else {
    char u[5] = {0};
    if (c < 0x800) {
      u[0] = (char)(0xC0 | (c >> 6));
      u[1] = (char)(0x80 | (c & 0x3F));
    } else if (c < 0x10000) {
      u[0] = (char)(0xE0 | (c >> 12));
      u[1] = (char)(0x80 | ((c >> 6) & 0x3F));
      u[2] = (char)(0x80 | (c & 0x3F));
    } else {
      u[0] = (char)(0xF0 | (c >> 18));
      u[1] = (char)(0x80 | ((c >> 12) & 0x3F));
      u[2] = (char)(0x80 | ((c >> 6) & 0x3F));
      u[3] = (char)(0x80 | (c & 0x3F));
    }
    snprintf(buf, n, "%s%s", alt, u);
  }
  return buf;
}

/* Shift on a US layout; the kitty report names the unshifted key. */
static int us_shift(int c) {
  static const char PLAIN[] = "`1234567890-=[]\\;',./";
  static const char SHIFTED[] = "~!@#$%^&*()_+{}|:\"<>?";
  if (c >= 'a' && c <= 'z')
    return c - 'a' + 'A';
  const char *p = c > 0 && c < 0x80 ? strchr(PLAIN, c) : NULL;
  return p ? SHIFTED[p - PLAIN] : c;
}

/* The control character xterm sends for ctrl+c, or c when there is none. */
static int ctrl_char(int c) {
  if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
    return c & 0x1f;
  switch (c) {
  case ' ': case '2': case '@': return 0;
  case '3': case '[': return 27;
  case '4': case '\\': return 28;
  case '5': case ']': return 29;
  case '6': case '^': return 30;
  case '7': case '-': case '_': case '/': return 31;
  case '8': case '?': return 127;
  default: return c;
  }
}

int cst_key_from_kitty(int cp, int mods, int out[2]) {
  int shift = mods & 1, alt = mods & 2, ctrl = mods & 4;
  if (mods & ~7)
    return 0; /* super, hyper, meta, caps/num lock: not ours */
  int c;
  switch (cp) {
  case 13:
    if (!mods)
      return out[0] = 13, 1;
    out[0] = 27, out[1] = 13; /* newline */
    return 2;
  case 127:
    if (!alt && !ctrl)
      return out[0] = 127, 1;
    out[0] = 27, out[1] = 127; /* delete word */
    return 2;
  case 9:
    if (shift && !alt && !ctrl)
      return out[0] = CST_K_BTAB, 1;
    c = 9;
    break;
  case 27:
    c = 27;
    break;
  default:
    if (cp < ' ' || cp > 0x10FFFF)
      return 0;
    c = shift ? us_shift(cp) : cp;
    if (ctrl)
      c = ctrl_char(c);
    break;
  }
  if (!alt)
    return out[0] = c, 1;
  out[0] = 27, out[1] = c;
  return 2;
}

/* "ctrl+x n", "<leader> n" or "f2" → keys; returns the count (0 on error). */
static int parse_seq(const cst_keymap_t *km, const char *s, int keys[2]) {
  int n = 0;
  while (*s) {
    while (*s == ' ')
      s++;
    if (!*s)
      break;
    size_t w = strcspn(s, " ");
    if (n == 2)
      return 0;
    int k = ieq(s, "<leader>", w) ? km->leader : parse_key_n(s, w);
    if (k < 0)
      return 0;
    keys[n++] = k;
    s += w;
  }
  return n;
}

static void add(cst_keymap_t *km, int action, const int keys[2], int nkeys,
                int user) {
  if (km->n >= CST_KEYMAP_MAX || nkeys < 1)
    return;
  cst_binding_t *b = &km->b[km->n++];
  b->action = action;
  b->keys[0] = keys[0];
  b->keys[1] = nkeys > 1 ? keys[1] : 0;
  b->nkeys = nkeys;
  b->user = user;
}

static void build_defaults(cst_keymap_t *km) {
  km->n = 0;
  for (size_t i = 0; i < sizeof(DEFAULTS) / sizeof(DEFAULTS[0]); i++) {
    int keys[2];
    int n = parse_seq(km, DEFAULTS[i].keys, keys);
    add(km, DEFAULTS[i].action, keys, n, 0);
  }
}

void cst_keymap_defaults(cst_keymap_t *km) {
  memset(km, 0, sizeof(*km));
  km->leader = 24; /* ctrl+x */
  build_defaults(km);
}

static void drop_action(cst_keymap_t *km, int action) {
  int o = 0;
  for (int i = 0; i < km->n; i++)
    if (km->b[i].action != action)
      km->b[o++] = km->b[i];
  km->n = o;
}

static void errf(char *err, size_t err_sz, int *bad, const char *what,
                 const char *name) {
  if (err && err_sz && !*bad)
    snprintf(err, err_sz, "keybinds.json: %s \"%.60s\"", what, name);
  *bad = 1;
}

int cst_keymap_apply_json(cst_keymap_t *km, const char *json, char *err,
                          size_t err_sz) {
  if (err && err_sz)
    err[0] = 0;
  cJSON *root = cJSON_Parse(json ? json : "");
  if (!cJSON_IsObject(root)) {
    cJSON_Delete(root);
    if (err && err_sz)
      snprintf(err, err_sz, "keybinds.json: not a JSON object");
    return -1;
  }
  int bad = 0;
  const cJSON *ld = cJSON_GetObjectItemCaseSensitive(root, "leader");
  if (cJSON_IsString(ld)) {
    int k = cst_key_parse(ld->valuestring);
    if (k > 0) {
      km->leader = k;
      build_defaults(km);
    } else {
      errf(err, err_sz, &bad, "bad leader key", ld->valuestring);
    }
  }
  const cJSON *it;
  cJSON_ArrayForEach(it, root) {
    if (!it->string || strcmp(it->string, "leader") == 0)
      continue;
    int action = cst_key_action_find(it->string);
    if (action == CST_KA_NONE) {
      errf(err, err_sz, &bad, "unknown action", it->string);
      continue;
    }
    drop_action(km, action);
    const cJSON *v;
    if (cJSON_IsString(it)) {
      if (strcmp(it->valuestring, "none") == 0)
        continue;
      int keys[2], n = parse_seq(km, it->valuestring, keys);
      if (n)
        add(km, action, keys, n, 1);
      else
        errf(err, err_sz, &bad, "bad key", it->valuestring);
    } else if (cJSON_IsArray(it)) {
      cJSON_ArrayForEach(v, it) {
        if (!cJSON_IsString(v))
          continue;
        int keys[2], n = parse_seq(km, v->valuestring, keys);
        if (n)
          add(km, action, keys, n, 1);
        else
          errf(err, err_sz, &bad, "bad key", v->valuestring);
      }
    } else {
      errf(err, err_sz, &bad, "expected a string or list for", it->string);
    }
  }
  cJSON_Delete(root);
  return bad ? -1 : 0;
}

int cst_keymap_load(cst_keymap_t *km, char *err, size_t err_sz) {
  cst_keymap_defaults(km);
  if (err && err_sz)
    err[0] = 0;
  char dir[OS_PATH_MAX], path[OS_PATH_MAX];
  if (os_config_dir(dir, sizeof(dir)) != 0 ||
      os_path_join(path, sizeof(path), dir, "keybinds.json") != 0)
    return 0;
  FILE *fp = fopen(path, "rb");
  if (!fp)
    return 0;
  char buf[16384];
  size_t n = fread(buf, 1, sizeof(buf) - 1, fp);
  fclose(fp);
  buf[n] = 0;
  return cst_keymap_apply_json(km, buf + cst_bom_len(buf, n), err, err_sz);
}

int cst_keymap_lookup(const cst_keymap_t *km, const int *seq, int n,
                      int *action) {
  int prefix = 0;
  for (int i = 0; i < km->n; i++) {
    const cst_binding_t *b = &km->b[i];
    if (b->keys[0] != seq[0])
      continue;
    if (b->nkeys == n && (n == 1 || b->keys[1] == seq[1])) {
      *action = b->action;
      return CST_KM_MATCH;
    }
    if (n == 1 && b->nkeys == 2)
      prefix = 1;
  }
  return prefix ? CST_KM_PREFIX : CST_KM_NONE;
}

static void seq_name(const cst_binding_t *b, char *buf, size_t n) {
  char a[32], c[32];
  cst_key_name(b->keys[0], a, sizeof(a));
  if (b->nkeys > 1)
    snprintf(buf, n, "%s %s", a, cst_key_name(b->keys[1], c, sizeof(c)));
  else
    snprintf(buf, n, "%s", a);
}

void cst_keymap_describe(const cst_keymap_t *km, int action, char *buf,
                         size_t n) {
  size_t o = 0;
  buf[0] = 0;
  for (int i = 0; i < km->n && o + 1 < n; i++) {
    if (km->b[i].action != action)
      continue;
    char s[80];
    seq_name(&km->b[i], s, sizeof(s));
    int w = snprintf(buf + o, n - o, "%s%s", o ? ", " : "", s);
    if (w < 0 || (size_t)w >= n - o)
      break;
    o += (size_t)w;
  }
}

int cst_keymap_conflicts(const cst_keymap_t *km, char *buf, size_t n) {
  int count = 0;
  size_t o = 0;
  if (n)
    buf[0] = 0;
  for (int i = 0; i < km->n; i++) {
    const cst_binding_t *a = &km->b[i];
    for (int j = i + 1; j < km->n; j++) {
      const cst_binding_t *b = &km->b[j];
      int same = a->keys[0] == b->keys[0] && a->nkeys == b->nkeys &&
                 (a->nkeys == 1 || a->keys[1] == b->keys[1]);
      int shadow = a->keys[0] == b->keys[0] && a->nkeys != b->nkeys;
      if ((!same && !shadow) || a->action == b->action)
        continue;
      count++;
      char s[80];
      seq_name(a->nkeys <= b->nkeys ? a : b, s, sizeof(s));
      if (o + 1 < n) {
        int w = snprintf(buf + o, n - o, "%s%s: %s, %s",
                         o ? "\n" : "", s, INFO[a->action].name,
                         INFO[b->action].name);
        if (w > 0 && (size_t)w < n - o)
          o += (size_t)w;
      }
    }
  }
  return count;
}