import React from 'react';
import { Button } from '@/components/ui/button';
import { ButtonLarge } from '@/components/ui/button-large';
import { Input } from '@/components/ui/input';
import { toast } from '@/components/ui';
import {
  Dialog,
  DialogContent,
  DialogDescription,
  DialogFooter,
  DialogHeader,
  DialogTitle,
} from '@/components/ui/dialog';
import {
  DropdownMenu,
  DropdownMenuContent,
  DropdownMenuItem,
  DropdownMenuTrigger,
} from '@/components/ui/dropdown-menu';
import { RiAddLine, RiAiAgentFill, RiAiAgentLine, RiDeleteBinLine, RiFileCopyLine, RiMore2Line, RiRobot2Line, RiRobotLine, RiRestartLine, RiEditLine } from '@remixicon/react';
import { useAgentsStore, isAgentBuiltIn, isAgentHidden, type AgentScope, type AgentDraft } from '@/stores/useAgentsStore';
import { useUIStore } from '@/stores/useUIStore';
import { useDeviceInfo } from '@/lib/device';
import { isVSCodeRuntime } from '@/lib/desktop';
import { cn } from '@/lib/utils';
import type { Agent } from '@opencode-ai/sdk/v2';
import { ScrollableOverlay } from '@/components/ui/ScrollableOverlay';

interface AgentsSidebarProps {
  onItemSelect?: () => void;
}

type PermissionAction = 'allow' | 'ask' | 'deny';
type PermissionRule = { permission: string; pattern: string; action: PermissionAction };

type PermissionConfigValue = PermissionAction | Record<string, PermissionAction>;

// OpenCode's built-in defaults for permissions that differ from "allow"
const getOpenCodeDefaultActionForPermission = (permissionName: string): PermissionAction => {
  if (permissionName === 'doom_loop' || permissionName === 'external_directory') {
    return 'ask';
  }
  return 'allow';
};

const toPermissionRuleset = (ruleset: unknown): PermissionRule[] => {
  if (!Array.isArray(ruleset)) {
    return [];
  }

  const parsed: PermissionRule[] = [];
  for (const entry of ruleset) {
    if (!entry || typeof entry !== 'object') {
      continue;
    }
    const candidate = entry as Partial<PermissionRule>;
    if (typeof candidate.permission !== 'string' || typeof candidate.pattern !== 'string' || typeof candidate.action !== 'string') {
      continue;
    }
    if (candidate.action !== 'allow' && candidate.action !== 'ask' && candidate.action !== 'deny') {
      continue;
    }
    parsed.push({ permission: candidate.permission, pattern: candidate.pattern, action: candidate.action });
  }

  return parsed;
};

const rulesetToPermissionConfig = (ruleset: unknown): AgentDraft['permission'] => {
  const parsed = toPermissionRuleset(ruleset);
  if (parsed.length === 0) {
    return undefined;
  }

  const byPermission: Record<string, Record<string, PermissionAction>> = {};
  for (const rule of parsed) {
    if (!rule.permission) {
      continue;
    }
    (byPermission[rule.permission] ||= {})[rule.pattern] = rule.action;
  }

  // Get the global default (wildcard * with pattern *)
  const globalDefault = byPermission['*']?.['*'];

  const permissionNames = Object.keys(byPermission);
  if (
    permissionNames.length === 1 &&
    permissionNames[0] === '*' &&
    Object.keys(byPermission['*'] || {}).length === 1 &&
    byPermission['*']?.['*']
  ) {
    return byPermission['*']['*'];
  }

  const result: Record<string, PermissionConfigValue> = {};
  for (const permissionName of permissionNames) {
    const map = byPermission[permissionName];
    const patterns = Object.keys(map);

    // For wildcard-only entries, check if they're redundant
    if (patterns.length === 1 && patterns[0] === '*' && permissionName !== '*') {
      const action = map['*'];
      const opencodeDefault = getOpenCodeDefaultActionForPermission(permissionName);

      // Skip if this permission is redundant (matches effective default)
      if (globalDefault) {
        if (action === globalDefault) continue;
      } else {
        if (action === opencodeDefault) continue;
      }

      result[permissionName] = action;
    } else if (permissionName === '*') {
      // Include global default
      if (patterns.length === 1 && patterns[0] === '*') {
        result[permissionName] = map['*'];
      } else {
        result[permissionName] = map;
      }
    } else {
      // Non-wildcard patterns - include as-is
      result[permissionName] = map;
    }
  }

  return Object.keys(result).length > 0 ? (result as AgentDraft['permission']) : undefined;
};

export const AgentsSidebar: React.FC<AgentsSidebarProps> = ({ onItemSelect }) => {
  const [renameDialogAgent, setRenameDialogAgent] = React.useState<Agent | null>(null);
  const [renameNewName, setRenameNewName] = React.useState('');

  const {
    selectedAgentName,
    agents,
    setSelectedAgent,
    setAgentDraft,
    createAgent,
    deleteAgent,
    loadAgents,
  } = useAgentsStore();

  const { setSidebarOpen } = useUIStore();
  const { isMobile } = useDeviceInfo();

  const [isDesktopRuntime, setIsDesktopRuntime] = React.useState<boolean>(() => {
    if (typeof window === 'undefined') return false;
    return typeof window.opencodeDesktop !== 'undefined';
  });

  const isVSCode = React.useMemo(() => isVSCodeRuntime(), []);

  React.useEffect(() => {
    if (typeof window === 'undefined') return;
    setIsDesktopRuntime(typeof window.opencodeDesktop !== 'undefined');
  }, []);

  React.useEffect(() => {
    loadAgents();
  }, [loadAgents]);

  const bgClass = isDesktopRuntime
    ? 'bg-transparent'
    : isVSCode
      ? 'bg-background'
      : 'bg-sidebar';

  const handleCreateNew = () => {
    // Generate unique name
    const baseName = 'new-agent';
    let newName = baseName;
    let counter = 1;
    while (agents.some((a) => a.name === newName)) {
      newName = `${baseName}-${counter}`;
      counter++;
    }

    // Set draft and open the page for editing
    setAgentDraft({ name: newName, scope: 'user' });
    setSelectedAgent(newName);
    onItemSelect?.();

    if (isMobile) {
      setSidebarOpen(false);
    }
  };

  const handleDeleteAgent = async (agent: Agent) => {
    if (isAgentBuiltIn(agent)) {
      toast.error('Built-in agents cannot be deleted');
      return;
    }

    if (window.confirm(`Are you sure you want to delete agent "${agent.name}"?`)) {
      const success = await deleteAgent(agent.name);
      if (success) {
        toast.success(`Agent "${agent.name}" deleted successfully`);
      } else {
        toast.error('Failed to delete agent');
      }
    }
  };

  const handleResetAgent = async (agent: Agent) => {
    if (!isAgentBuiltIn(agent)) {
      return;
    }

    if (window.confirm(`Are you sure you want to reset agent "${agent.name}" to its default configuration?`)) {
      const success = await deleteAgent(agent.name);
      if (success) {
        toast.success(`Agent "${agent.name}" reset to default`);
      } else {
        toast.error('Failed to reset agent');
      }
    }
  };

  const handleDuplicateAgent = (agent: Agent) => {
    const baseName = agent.name;
    let copyNumber = 1;
    let newName = `${baseName}-copy`;

    while (agents.some((a) => a.name === newName)) {
      copyNumber++;
      newName = `${baseName}-copy-${copyNumber}`;
    }

    // Set draft with prefilled values from source agent
    const extAgent = agent as Agent & { scope?: AgentScope };
    const modelStr = agent.model?.providerID && agent.model?.modelID
      ? `${agent.model.providerID}/${agent.model.modelID}`
      : null;
    const draftAgent = agent as Agent & { disable?: boolean };
    setAgentDraft({
      name: newName,
      scope: extAgent.scope || 'user',
      description: agent.description,
      model: modelStr,
      temperature: agent.temperature,
      top_p: agent.topP,
      prompt: agent.prompt,
      mode: agent.mode,
      permission: rulesetToPermissionConfig(agent.permission),
      disable: draftAgent.disable,
    });
    setSelectedAgent(newName);

    if (isMobile) {
      setSidebarOpen(false);
    }
  };

  const handleOpenRenameDialog = (agent: Agent) => {
    setRenameNewName(agent.name);
    setRenameDialogAgent(agent);
  };

  const handleRenameAgent = async () => {
    if (!renameDialogAgent) return;

    const sanitizedName = renameNewName.trim().replace(/\s+/g, '-');

    if (!sanitizedName) {
      toast.error('Agent name is required');
      return;
    }

    if (sanitizedName === renameDialogAgent.name) {
      setRenameDialogAgent(null);
      return;
    }

    if (agents.some((a) => a.name === sanitizedName)) {
      toast.error('An agent with this name already exists');
      return;
    }

    // Create new agent with new name and all existing config
    const renameModelStr = renameDialogAgent.model?.providerID && renameDialogAgent.model?.modelID
      ? `${renameDialogAgent.model.providerID}/${renameDialogAgent.model.modelID}`
      : null;
    const renameExt = renameDialogAgent as Agent & { scope?: AgentScope; disable?: boolean };
    const success = await createAgent({
      name: sanitizedName,
      description: renameDialogAgent.description,
      model: renameModelStr,
      temperature: renameDialogAgent.temperature,
      top_p: renameDialogAgent.topP,
      prompt: renameDialogAgent.prompt,
      mode: renameDialogAgent.mode,
      permission: rulesetToPermissionConfig(renameDialogAgent.permission),
      disable: renameExt.disable,
      scope: renameExt.scope,
    });

    if (success) {
      // Delete old agent
      const deleteSuccess = await deleteAgent(renameDialogAgent.name);
      if (deleteSuccess) {
        toast.success(`Agent renamed to "${sanitizedName}"`);
        setSelectedAgent(sanitizedName);
      } else {
        toast.error('Failed to remove old agent after rename');
      }
    } else {
      toast.error('Failed to rename agent');
    }

    setRenameDialogAgent(null);
  };

  const getAgentModeIcon = (mode?: string) => {
    switch (mode) {
      case 'primary':
        return <RiAiAgentLine className="h-3 w-3 text-primary" />;
      case 'all':
        return <RiAiAgentFill className="h-3 w-3 text-primary" />;
      case 'subagent':
        return <RiRobotLine className="h-3 w-3 text-primary" />;
      default:
        return null;
    }
  };

  // Filter out hidden agents (internal agents like title, compaction, summary)
  const visibleAgents = agents.filter((agent) => !isAgentHidden(agent));
  const builtInAgents = visibleAgents.filter(isAgentBuiltIn);
  const customAgents = visibleAgents.filter((agent) => !isAgentBuiltIn(agent));

  return (
    <div className={cn('flex h-full flex-col', bgClass)}>
      <div className={cn('border-b px-3', isMobile ? 'mt-2 py-3' : 'py-3')}>
        <div className="flex items-center justify-between gap-2">
          <span className="typography-meta text-muted-foreground">Total {visibleAgents.length}</span>
          <Button
            type="button"
            variant="ghost"
            size="icon"
            className="h-7 w-7 -my-1 text-muted-foreground"
            onClick={handleCreateNew}
          >
            <RiAddLine className="size-4" />
          </Button>
        </div>
      </div>

      <ScrollableOverlay outerClassName="flex-1 min-h-0" className="space-y-1 px-3 py-2 overflow-x-hidden">
        {visibleAgents.length === 0 ? (
          <div className="py-12 px-4 text-center text-muted-foreground">
            <RiRobot2Line className="mx-auto mb-3 h-10 w-10 opacity-50" />
            <p className="typography-ui-label font-medium">No agents configured</p>
            <p className="typography-meta mt-1 opacity-75">Use the + button above to create one</p>
          </div>
        ) : (
          <>
            {builtInAgents.length > 0 && (
              <>
                <div className="px-2 pb-1.5 pt-2 text-xs font-semibold uppercase tracking-wide text-muted-foreground">
                  Built-in Agents
                </div>
                {builtInAgents.map((agent) => (
                  <AgentListItem
                    key={agent.name}
                    agent={agent}
                    isSelected={selectedAgentName === agent.name}
                    onSelect={() => {
                      setSelectedAgent(agent.name);
                      onItemSelect?.();
                      if (isMobile) {
                        setSidebarOpen(false);
                      }
                    }}
                    onReset={() => handleResetAgent(agent)}
                    onDuplicate={() => handleDuplicateAgent(agent)}
                    getAgentModeIcon={getAgentModeIcon}
                  />
                ))}
              </>
            )}

            {customAgents.length > 0 && (
              <>
                <div className="px-2 pb-1.5 pt-3 text-xs font-semibold uppercase tracking-wide text-muted-foreground">
                  Custom Agents
                </div>
                {customAgents.map((agent) => (
                  <AgentListItem
                    key={agent.name}
                    agent={agent}
                    isSelected={selectedAgentName === agent.name}
                    onSelect={() => {
                      setSelectedAgent(agent.name);
                      onItemSelect?.();
                      if (isMobile) {
                        setSidebarOpen(false);
                      }
                    }}
                    onRename={() => handleOpenRenameDialog(agent)}
                    onDelete={() => handleDeleteAgent(agent)}
                    onDuplicate={() => handleDuplicateAgent(agent)}
                    getAgentModeIcon={getAgentModeIcon}
                  />
                ))}
              </>
            )}
          </>
        )}
      </ScrollableOverlay>

      {/* Rename Dialog */}
      <Dialog open={renameDialogAgent !== null} onOpenChange={(open) => !open && setRenameDialogAgent(null)}>
        <DialogContent>
          <DialogHeader>
            <DialogTitle>Rename Agent</DialogTitle>
            <DialogDescription>
              Enter a new name for the agent "@{renameDialogAgent?.name}"
            </DialogDescription>
          </DialogHeader>
          <Input
            value={renameNewName}
            onChange={(e) => setRenameNewName(e.target.value)}
            placeholder="New agent name..."
            className="text-foreground placeholder:text-muted-foreground"
            onKeyDown={(e) => {
              if (e.key === 'Enter') {
                handleRenameAgent();
              }
            }}
          />
          <DialogFooter>
            <Button
              variant="ghost"
              onClick={() => setRenameDialogAgent(null)}
              className="text-foreground hover:bg-muted hover:text-foreground"
            >
              Cancel
            </Button>
            <ButtonLarge onClick={handleRenameAgent}>
              Rename
            </ButtonLarge>
          </DialogFooter>
        </DialogContent>
      </Dialog>
    </div>
  );
};

interface AgentListItemProps {
  agent: Agent;
  isSelected: boolean;
  onSelect: () => void;
  onDelete?: () => void;
  onReset?: () => void;
  onRename?: () => void;
  onDuplicate: () => void;
  getAgentModeIcon: (mode?: string) => React.ReactNode;
}

const AgentListItem: React.FC<AgentListItemProps> = ({
  agent,
  isSelected,
  onSelect,
  onDelete,
  onReset,
  onRename,
  onDuplicate,
  getAgentModeIcon,
}) => {
  const extAgent = agent as Agent & { scope?: AgentScope };
  
  return (
    <div
      className={cn(
        'group relative flex items-center rounded-md px-1.5 py-1 transition-all duration-200',
        isSelected ? 'dark:bg-accent/80 bg-primary/12' : 'hover:dark:bg-accent/40 hover:bg-primary/6'
      )}
    >
      <div className="flex min-w-0 flex-1 items-center">
        <button
          onClick={onSelect}
          className="flex min-w-0 flex-1 flex-col gap-0 rounded-sm text-left focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-primary/50"
          tabIndex={0}
        >
          <div className="flex items-center gap-1.5">
            <span className="typography-ui-label font-normal truncate text-foreground">
              {agent.name}
            </span>
            {getAgentModeIcon(agent.mode)}
            {(extAgent.scope || isAgentBuiltIn(agent)) && (
              <span className="typography-micro text-muted-foreground bg-muted px-1 rounded flex-shrink-0 leading-none pb-px border border-border/50">
                {isAgentBuiltIn(agent) ? 'system' : extAgent.scope}
              </span>
            )}
          </div>

          {agent.description && (
            <div className="typography-micro text-muted-foreground/60 truncate leading-tight">
              {agent.description}
            </div>
          )}
        </button>

        <DropdownMenu>
          <DropdownMenuTrigger asChild>
            <Button
              size="icon"
              variant="ghost"
              className="h-6 w-6 flex-shrink-0 -mr-1 opacity-100 transition-opacity md:opacity-0 md:group-hover:opacity-100"
            >
              <RiMore2Line className="h-3.5 w-3.5" />
            </Button>
          </DropdownMenuTrigger>
          <DropdownMenuContent align="end" className="w-fit min-w-20">
            {onRename && (
              <DropdownMenuItem
                onClick={(e) => {
                  e.stopPropagation();
                  onRename();
                }}
              >
                <RiEditLine className="h-4 w-4 mr-px" />
                Rename
              </DropdownMenuItem>
            )}

            <DropdownMenuItem
              onClick={(e) => {
                e.stopPropagation();
                onDuplicate();
              }}
            >
              <RiFileCopyLine className="h-4 w-4 mr-px" />
              Duplicate
            </DropdownMenuItem>

            {onReset && (
              <DropdownMenuItem
                onClick={(e) => {
                  e.stopPropagation();
                  onReset();
                }}
              >
                <RiRestartLine className="h-4 w-4 mr-px" />
                Reset
              </DropdownMenuItem>
            )}

            {onDelete && (
              <DropdownMenuItem
                onClick={(e) => {
                  e.stopPropagation();
                  onDelete();
                }}
                className="text-destructive focus:text-destructive"
              >
                <RiDeleteBinLine className="h-4 w-4 mr-px" />
                Delete
              </DropdownMenuItem>
            )}
          </DropdownMenuContent>
        </DropdownMenu>
      </div>
    </div>
  );
};