/**
 * Agent config keys to display names mapping.
 * Config keys are lowercase (e.g., "sisyphus", "atlas").
 * Display names include suffixes for UI/logs (e.g., "Sisyphus - Ultraworker").
 *
 * IMPORTANT: Display names MUST NOT contain parentheses or other characters
 * that are invalid in HTTP header values per RFC 7230. OpenCode passes the
 * agent name in the `x-opencode-agent-name` header, and parentheses cause
 * header validation failures that prevent agents from appearing in the UI
 * type selector dropdown. Use ` - ` (space-dash-space) instead of `(...)`.
 */
export const AGENT_DISPLAY_NAMES: Record<string, string> = {
  sisyphus: "Sisyphus - Ultraworker",
  hephaestus: "Hephaestus - Deep Agent",
  prometheus: "Prometheus - Plan Builder",
  atlas: "Atlas - Plan Executor",
  "sisyphus-junior": "Sisyphus-Junior",
  metis: "Metis - Plan Consultant",
  momus: "Momus - Plan Critic",
  athena: "Athena - Council",
  "athena-junior": "Athena-Junior - Council",
  oracle: "oracle",
  librarian: "librarian",
  explore: "explore",
  "multimodal-looker": "multimodal-looker",
  "council-member": "council-member",
}

const AGENT_LIST_SORT_PREFIXES: Record<string, string> = {
  sisyphus: "\u200B",
  hephaestus: "\u200B\u200B",
  prometheus: "\u200B\u200B\u200B",
  atlas: "\u200B\u200B\u200B\u200B",
}

function stripAgentListSortPrefix(agentName: string): string {
  return agentName.replace(/^\u200B+/, "")
}

/**
 * Get display name for an agent config key.
 * Uses case-insensitive lookup for backward compatibility.
 * Returns original key if not found.
 */
export function getAgentDisplayName(configKey: string): string {
  // Try exact match first
  const exactMatch = AGENT_DISPLAY_NAMES[configKey]
  if (exactMatch !== undefined) return exactMatch
  
  // Fall back to case-insensitive search
  const lowerKey = configKey.toLowerCase()
  for (const [k, v] of Object.entries(AGENT_DISPLAY_NAMES)) {
    if (k.toLowerCase() === lowerKey) return v
  }
  
  // Unknown agent: return original key
  return configKey
}

export function getAgentListDisplayName(configKey: string): string {
  const displayName = getAgentDisplayName(configKey)
  const prefix = AGENT_LIST_SORT_PREFIXES[configKey.toLowerCase()]

  return prefix ? `${prefix}${displayName}` : displayName
}

const REVERSE_DISPLAY_NAMES: Record<string, string> = Object.fromEntries(
  Object.entries(AGENT_DISPLAY_NAMES).map(([key, displayName]) => [displayName.toLowerCase(), key]),
)

// Legacy parenthesized display names for backward compatibility.
// Old configs/sessions may reference these names; resolve them to config keys.
const LEGACY_DISPLAY_NAMES: Record<string, string> = {
  "sisyphus (ultraworker)": "sisyphus",
  "hephaestus (deep agent)": "hephaestus",
  "prometheus (plan builder)": "prometheus",
  "atlas (plan executor)": "atlas",
  "metis (plan consultant)": "metis",
  "momus (plan critic)": "momus",
  "athena (council)": "athena",
  "athena-junior (council)": "athena-junior",
}

/**
 * Resolve an agent name (display name or config key) to its lowercase config key.
 * "Atlas - Plan Executor" -> "atlas", "Atlas (Plan Executor)" -> "atlas", "atlas" -> "atlas"
 */
export function getAgentConfigKey(agentName: string): string {
  const lower = stripAgentListSortPrefix(agentName).toLowerCase()
  const reversed = REVERSE_DISPLAY_NAMES[lower]
  if (reversed !== undefined) return reversed
  const legacy = LEGACY_DISPLAY_NAMES[lower]
  if (legacy !== undefined) return legacy
  if (AGENT_DISPLAY_NAMES[lower] !== undefined) return lower
  return lower
}

/**
 * Normalize an agent name for prompt APIs.
 * - Known display names -> canonical display names
 * - Known config keys (any case) -> canonical display names
 * - Unknown/custom names -> preserved as-is (trimmed)
 */
export function normalizeAgentForPrompt(agentName: string | undefined): string | undefined {
  if (typeof agentName !== "string") {
    return undefined
  }

  const trimmed = stripAgentListSortPrefix(agentName.trim())
  if (!trimmed) {
    return undefined
  }

  const lower = trimmed.toLowerCase()
  const reversed = REVERSE_DISPLAY_NAMES[lower]
  if (reversed !== undefined) {
    return AGENT_DISPLAY_NAMES[reversed] ?? trimmed
  }
  const legacy = LEGACY_DISPLAY_NAMES[lower]
  if (legacy !== undefined) {
    return AGENT_DISPLAY_NAMES[legacy] ?? trimmed
  }
  if (AGENT_DISPLAY_NAMES[lower] !== undefined) {
    return AGENT_DISPLAY_NAMES[lower]
  }

  return trimmed
}

export function normalizeAgentForPromptKey(agentName: string | undefined): string | undefined {
  if (typeof agentName !== "string") {
    return undefined
  }

  const trimmed = stripAgentListSortPrefix(agentName.trim())
  if (!trimmed) {
    return undefined
  }

  const lower = trimmed.toLowerCase()
  const reversed = REVERSE_DISPLAY_NAMES[lower]
  if (reversed !== undefined) {
    return reversed
  }
  const legacy = LEGACY_DISPLAY_NAMES[lower]
  if (legacy !== undefined) {
    return legacy
  }
  if (AGENT_DISPLAY_NAMES[lower] !== undefined) {
    return lower
  }

  return trimmed
}