import { useState, useEffect, useCallback } from "react";
import type { JSX } from "react";
import { X, Plus, Play, Pause, Square, Activity, Heart, Trash2, RefreshCw, Bot } from "lucide-react";
import type { Agent, AgentCapability, AgentState } from "../api";
import { fetchAgents, createAgent, updateAgentState, deleteAgent } from "../api";

interface AgentListModalProps {
  isOpen: boolean;
  onClose: () => void;
  addToast: (message: string, type?: "success" | "error") => void;
}

const AGENT_ROLES: { value: AgentCapability; label: string; icon: string }[] = [
  { value: "triage", label: "Triage", icon: "🔍" },
  { value: "executor", label: "Executor", icon: "⚡" },
  { value: "reviewer", label: "Reviewer", icon: "👁" },
  { value: "merger", label: "Merger", icon: "🔀" },
  { value: "scheduler", label: "Scheduler", icon: "⏰" },
  { value: "custom", label: "Custom", icon: "🔧" },
];

const STATE_COLORS: Record<AgentState, { bg: string; text: string; border: string }> = {
  idle: { bg: "var(--state-idle-bg)", text: "var(--state-idle-text)", border: "var(--state-idle-border)" },
  active: { bg: "var(--state-active-bg)", text: "var(--state-active-text)", border: "var(--state-active-border)" },
  paused: { bg: "var(--state-paused-bg)", text: "var(--state-paused-text)", border: "var(--state-paused-border)" },
  terminated: { bg: "var(--state-error-bg)", text: "var(--state-error-text)", border: "var(--state-error-border)" },
};

export function AgentListModal({ isOpen, onClose, addToast }: AgentListModalProps) {
  const [agents, setAgents] = useState<Agent[]>([]);
  const [isLoading, setIsLoading] = useState(false);
  const [isCreating, setIsCreating] = useState(false);
  const [newAgentName, setNewAgentName] = useState("");
  const [newAgentRole, setNewAgentRole] = useState<AgentCapability>("custom");
  const [filterState, setFilterState] = useState<AgentState | "all">("all");

  const loadAgents = useCallback(async () => {
    setIsLoading(true);
    try {
      const filter = filterState !== "all" ? { state: filterState } : undefined;
      const data = await fetchAgents(filter);
      setAgents(data);
    } catch (err: any) {
      addToast(`Failed to load agents: ${err.message}`, "error");
    } finally {
      setIsLoading(false);
    }
  }, [filterState, addToast]);

  useEffect(() => {
    if (isOpen) {
      void loadAgents();
    }
  }, [isOpen, loadAgents]);

  const handleCreate = async () => {
    if (!newAgentName.trim()) return;
    try {
      await createAgent({ name: newAgentName.trim(), role: newAgentRole });
      addToast(`Agent "${newAgentName}" created`, "success");
      setNewAgentName("");
      setIsCreating(false);
      void loadAgents();
    } catch (err: any) {
      addToast(`Failed to create agent: ${err.message}`, "error");
    }
  };

  const handleStateChange = async (agentId: string, newState: AgentState) => {
    try {
      await updateAgentState(agentId, newState);
      addToast(`Agent state updated to ${newState}`, "success");
      void loadAgents();
    } catch (err: any) {
      addToast(`Failed to update state: ${err.message}`, "error");
    }
  };

  const handleDelete = async (agentId: string, agentName: string) => {
    if (!confirm(`Delete agent "${agentName}"? This cannot be undone.`)) return;
    try {
      await deleteAgent(agentId);
      addToast(`Agent "${agentName}" deleted`, "success");
      void loadAgents();
    } catch (err: any) {
      addToast(`Failed to delete agent: ${err.message}`, "error");
    }
  };

  const getRoleLabel = (role: AgentCapability) => AGENT_ROLES.find(r => r.value === role)?.label ?? role;
  const getRoleIcon = (role: AgentCapability) => AGENT_ROLES.find(r => r.value === role)?.icon ?? "🤖";

  const getHealthStatus = (agent: Agent): { label: string; icon: JSX.Element; color: string } => {
    if (agent.state === "terminated") {
      return { label: "Terminated", icon: <Square size={14} />, color: "var(--state-error-text)" };
    }
    if (agent.state === "paused") {
      return { label: "Paused", icon: <Pause size={14} />, color: "var(--state-paused-text)" };
    }
    if (!agent.lastHeartbeatAt) {
      return { label: agent.state === "active" ? "Starting..." : "Idle", icon: <Bot size={14} />, color: "var(--text-secondary)" };
    }
    const lastHeartbeat = new Date(agent.lastHeartbeatAt).getTime();
    const elapsed = Date.now() - lastHeartbeat;
    const timeoutMs = 60000; // 60 second timeout
    if (elapsed > timeoutMs) {
      return { label: "Unresponsive", icon: <Activity size={14} />, color: "var(--state-error-text)" };
    }
    return { label: "Healthy", icon: <Heart size={14} />, color: "var(--state-active-text)" };
  };

  if (!isOpen) return null;

  return (
    <div className="modal-overlay" onClick={(e) => e.target === e.currentTarget && onClose()}>
      <div className="modal modal--wide">
        <div className="modal-header">
          <h2 className="modal-title">
            <Bot size={20} />
            Agents
          </h2>
          <div className="modal-actions">
            <button
              className="btn-icon"
              onClick={() => void loadAgents()}
              title="Refresh"
              disabled={isLoading}
            >
              <RefreshCw size={16} className={isLoading ? "spin" : ""} />
            </button>
            <button className="btn-icon" onClick={onClose} title="Close">
              <X size={20} />
            </button>
          </div>
        </div>

        <div className="modal-content">
          {/* Filter and Create Bar */}
          <div className="agent-controls">
            <select
              className="select"
              value={filterState}
              onChange={(e) => setFilterState(e.target.value as AgentState | "all")}
            >
              <option value="all">All States</option>
              <option value="idle">Idle</option>
              <option value="active">Active</option>
              <option value="paused">Paused</option>
              <option value="terminated">Terminated</option>
            </select>

            <button
              className="btn btn--primary"
              onClick={() => setIsCreating(!isCreating)}
            >
              <Plus size={16} />
              {isCreating ? "Cancel" : "New Agent"}
            </button>
          </div>

          {/* Create Form */}
          {isCreating && (
            <div className="agent-create-form">
              <input
                type="text"
                placeholder="Agent name..."
                value={newAgentName}
                onChange={(e) => setNewAgentName(e.target.value)}
                onKeyDown={(e) => e.key === "Enter" && handleCreate()}
                className="input"
                autoFocus
              />
              <select
                className="select"
                value={newAgentRole}
                onChange={(e) => setNewAgentRole(e.target.value as AgentCapability)}
              >
                {AGENT_ROLES.map(role => (
                  <option key={role.value} value={role.value}>
                    {role.icon} {role.label}
                  </option>
                ))}
              </select>
              <button className="btn btn--primary" onClick={() => void handleCreate()}>
                Create
              </button>
            </div>
          )}

          {/* Agent List */}
          <div className="agent-list">
            {agents.length === 0 ? (
              <div className="agent-empty">
                <Bot size={48} opacity={0.3} />
                <p>No agents found</p>
                <p className="text-secondary">Create an agent to get started</p>
              </div>
            ) : (
              agents.map(agent => {
                const health = getHealthStatus(agent);
                const stateStyle = STATE_COLORS[agent.state];
                return (
                  <div key={agent.id} className="agent-card" style={{ borderLeftColor: stateStyle.border }}>
                    <div className="agent-card-header">
                      <div className="agent-info">
                        <span className="agent-icon">{getRoleIcon(agent.role)}</span>
                        <div className="agent-meta">
                          <span className="agent-name">{agent.name}</span>
                          <span className="agent-id text-secondary">{agent.id}</span>
                        </div>
                      </div>
                      <div className="agent-badges">
                        <span
                          className="badge"
                          style={{
                            background: stateStyle.bg,
                            color: stateStyle.text,
                            border: `1px solid ${stateStyle.border}`,
                          }}
                        >
                          {agent.state}
                        </span>
                        <span className="badge" style={{ color: health.color }}>
                          {health.icon} {health.label}
                        </span>
                        <span className="badge text-secondary">
                          {getRoleLabel(agent.role)}
                        </span>
                      </div>
                    </div>

                    <div className="agent-card-body">
                      {agent.taskId && (
                        <div className="agent-task">
                          <span className="text-secondary">Working on:</span>
                          <span className="badge">{agent.taskId}</span>
                        </div>
                      )}
                      {agent.lastHeartbeatAt && (
                        <div className="agent-heartbeat">
                          <span className="text-secondary">Last heartbeat:</span>
                          <span>{new Date(agent.lastHeartbeatAt).toLocaleString()}</span>
                        </div>
                      )}
                    </div>

                    <div className="agent-card-actions">
                      {agent.state === "idle" && (
                        <button
                          className="btn btn--sm"
                          onClick={() => void handleStateChange(agent.id, "active")}
                          title="Activate"
                        >
                          <Play size={14} /> Start
                        </button>
                      )}
                      {agent.state === "active" && (
                        <>
                          <button
                            className="btn btn--sm"
                            onClick={() => void handleStateChange(agent.id, "paused")}
                            title="Pause"
                          >
                            <Pause size={14} /> Pause
                          </button>
                          <button
                            className="btn btn--sm btn--danger"
                            onClick={() => void handleStateChange(agent.id, "terminated")}
                            title="Stop"
                          >
                            <Square size={14} /> Stop
                          </button>
                        </>
                      )}
                      {agent.state === "paused" && (
                        <>
                          <button
                            className="btn btn--sm"
                            onClick={() => void handleStateChange(agent.id, "active")}
                            title="Resume"
                          >
                            <Play size={14} /> Resume
                          </button>
                          <button
                            className="btn btn--sm btn--danger"
                            onClick={() => void handleStateChange(agent.id, "terminated")}
                            title="Stop"
                          >
                            <Square size={14} /> Stop
                          </button>
                        </>
                      )}
                      {agent.state === "terminated" && (
                        <button
                          className="btn btn--sm btn--danger"
                          onClick={() => void handleDelete(agent.id, agent.name)}
                          title="Delete"
                        >
                          <Trash2 size={14} /> Delete
                        </button>
                      )}
                    </div>
                  </div>
                );
              })
            )}
          </div>
        </div>
      </div>

      <style>{`
        :host, .modal--wide {
          /* Agent state CSS variables - define fallback values */
          --state-idle-bg: rgba(139, 148, 158, 0.15);
          --state-idle-text: #8b949e;
          --state-idle-border: #8b949e;
          --state-active-bg: rgba(46, 160, 67, 0.15);
          --state-active-text: #3fb950;
          --state-active-border: #3fb950;
          --state-paused-bg: rgba(227, 179, 65, 0.15);
          --state-paused-text: #e3b541;
          --state-paused-border: #e3b541;
          --state-error-bg: rgba(248, 81, 73, 0.15);
          --state-error-text: #f85149;
          --state-error-border: #f85149;
          --text-secondary: var(--text-muted, #8b949e);
        }

        .modal--wide {
          width: 90vw;
          max-width: 900px;
          max-height: 80vh;
        }

        .modal-content {
          padding: 20px;
          overflow-y: auto;
        }

        .agent-controls {
          display: flex;
          gap: 12px;
          margin-bottom: 16px;
        }

        .agent-controls .select {
          width: auto;
        }

        .agent-create-form {
          display: flex;
          gap: 12px;
          margin-bottom: 16px;
          padding: 16px;
          background: var(--bg-secondary);
          border-radius: 8px;
        }

        .agent-create-form .input {
          flex: 1;
        }

        .agent-list {
          display: flex;
          flex-direction: column;
          gap: 12px;
        }

        .agent-empty {
          display: flex;
          flex-direction: column;
          align-items: center;
          padding: 48px;
          color: var(--text-secondary);
        }

        .agent-card {
          border: 1px solid var(--border);
          border-left-width: 4px;
          border-radius: 8px;
          padding: 16px;
          background: var(--bg-primary);
        }

        .agent-card-header {
          display: flex;
          justify-content: space-between;
          align-items: flex-start;
          margin-bottom: 12px;
        }

        .agent-info {
          display: flex;
          align-items: center;
          gap: 12px;
        }

        .agent-icon {
          font-size: 24px;
        }

        .agent-meta {
          display: flex;
          flex-direction: column;
        }

        .agent-name {
          font-weight: 600;
          font-size: 16px;
        }

        .agent-id {
          font-size: 12px;
          font-family: var(--font-mono);
        }

        .agent-badges {
          display: flex;
          gap: 8px;
          flex-wrap: wrap;
        }

        .agent-card-body {
          display: flex;
          flex-direction: column;
          gap: 4px;
          margin-bottom: 12px;
          padding: 8px;
          background: var(--bg-secondary);
          border-radius: 4px;
          font-size: 13px;
        }

        .agent-task,
        .agent-heartbeat {
          display: flex;
          gap: 8px;
        }

        .agent-card-actions {
          display: flex;
          gap: 8px;
        }

        .spin {
          animation: spin 1s linear infinite;
        }

        @keyframes spin {
          from { transform: rotate(0deg); }
          to { transform: rotate(360deg); }
        }

        .text-secondary {
          color: var(--text-secondary);
        }
      `}</style>
    </div>
  );
}