/**
 * Shared utilities for the Settings page.
 * Centralises constants, URL helpers, normalisation functions and validation
 * helpers that are consumed by +page.svelte and EnvironmentsTab.svelte.
 */

// ---------------------------------------------------------------------------
// Constants
// ---------------------------------------------------------------------------

export const SETTINGS_TABS = [
  "environments",
  "connections",
  "logging",
  "git",
  "llm",
  "migration",
  "storage",
  "features",
  "reports",
  "automation",
  "languages",
  "system",
] as const;

export type SettingsTab = typeof SETTINGS_TABS[number];

interface LlmPrompts {
  documentation_prompt: string;
  git_commit_prompt: string;
}

interface LlmProviderBindings {
  documentation: string;
  git_commit: string;
}

interface LlmSettings {
  prompts?: Partial<LlmPrompts>;
  provider_bindings?: Partial<LlmProviderBindings>;
  [key: string]: unknown;
}

export const DEFAULT_LLM_PROMPTS: LlmPrompts = {
  documentation_prompt:
    'Generate professional documentation for the following dataset and its columns.\nDataset: {dataset_name}\nColumns: {columns_json}\n\nProvide the documentation in JSON format:\n{\n    \"dataset_description\": \"General description of the dataset\",\n    \"column_descriptions\": [\n        {\n            \"name\": \"column_name\",\n            \"description\": \"Generated description\"\n        }\n    ]\n}',
  git_commit_prompt:
    'Generate a concise and professional git commit message based on the following diff and recent history.\nUse Conventional Commits format (e.g., feat: ..., fix: ..., docs: ...).\n\nRecent History:\n{history}\n\nDiff:\n{diff}\n\nCommit Message:',
};

export const DEFAULT_LLM_PROVIDER_BINDINGS: LlmProviderBindings = {
  documentation: "",
  git_commit: "",
};

// ---------------------------------------------------------------------------
// URL tab helpers
// ---------------------------------------------------------------------------

/**
 * Read the current settings tab from the URL hash fragment.
 * Falls back to "environments" when the hash is missing or invalid.
 */
export function readTabFromUrl(): string {
  const hash = typeof window !== "undefined" ? window.location.hash : "";
  const tab = hash.replace(/^#\/?settings\//, "") || "";
  return normalizeTab(tab) || "environments";
}

/**
 * Write the active settings tab to the URL hash fragment so it survives
 * browser refreshes and can be linked to directly.
 */
export function writeTabToUrl(tab: string): void {
  if (typeof window === "undefined") return;
  const normalized = normalizeTab(tab);
  if (normalized) {
    window.location.hash = `/settings/${normalized}`;
  }
}

/**
 * Normalise an arbitrary tab identifier to a valid tab key, or return null
 * when the identifier does not match any known tab.
 */
export function normalizeTab(tab: string): string | null {
  if (!tab || typeof tab !== "string") return null;
  const candidate = tab.trim().toLowerCase();
  return SETTINGS_TABS.includes(candidate as SettingsTab) ? candidate : null;
}

// ---------------------------------------------------------------------------
// LLM helpers
// ---------------------------------------------------------------------------

/**
 * Merge incoming LLM settings with the default prompts and bindings so that
 * individual fields are never accidentally set to `undefined`.
 */
export function normalizeLlmSettings(llm: LlmSettings | null | undefined): LlmSettings {
  if (!llm || typeof llm !== "object") {
    return {
      prompts: { ...DEFAULT_LLM_PROMPTS },
      provider_bindings: { ...DEFAULT_LLM_PROVIDER_BINDINGS },
    };
  }
  return {
    ...llm,
    prompts: { ...DEFAULT_LLM_PROMPTS, ...llm.prompts },
    provider_bindings: {
      ...DEFAULT_LLM_PROVIDER_BINDINGS,
      ...llm.provider_bindings,
    },
  };
}

// ---------------------------------------------------------------------------
// Environment helpers
// ---------------------------------------------------------------------------

/**
 * Strip trailing slashes and the `/api/v1` suffix from a Superset base URL,
 * auto-prepend https:// if no scheme is present,
 * returning a clean base URL suitable for constructing dashboard links.
 */
export function normalizeSupersetBaseUrl(rawUrl: string): string | null {
  let baseUrl = String(rawUrl || "").trim().replace(/\/+$/, "");
  if (!baseUrl) return null;
  if (baseUrl.endsWith("/api/v1")) {
    baseUrl = baseUrl.slice(0, -"/api/v1".length);
  }
  // Auto-prepend https:// if no scheme is present
  if (baseUrl && !/^https?:\/\//i.test(baseUrl)) {
    baseUrl = `https://${baseUrl}`;
  }
  return baseUrl;
}

/**
 * Classify an environment's deployment stage from its `name` or `url`.
 * Returns one of: `"PROD"`, `"PREPROD"`, or `"DEV"`.
 */
export function resolveEnvStage(env: { name?: string; url?: string } | null | undefined): string {
  if (!env) return "DEV";
  const needle = ((env.name || "") + " " + (env.url || "")).toLowerCase();
  if (/prod(uction)?/.test(needle) && !/preprod/.test(needle)) return "PROD";
  if (/preprod|staging|stage/.test(needle)) return "PREPROD";
  return "DEV";
}

// ---------------------------------------------------------------------------
// Connection draft helper
// ---------------------------------------------------------------------------