/**
 * The shared settings-PUT body parsers — one seam per settings surface.
 * Extracted verbatim from the per-chat route (default-settings wave,
 * 2026-09-18): identical parse, identical errors. The section parsers
 * (settings-storage wave, 2026-09-19) follow the same house rules.
 *
 * Replace-whole semantics: the client sends the complete desired SECTION;
 * absent fields are absent overrides ({} clears everything). No merges, so
 * a stale client can never resurrect a cleared override. Unknown body keys
 * are dropped (same tolerance as parseSettingsBody) — unknown DISK keys are
 * a different concern and are preserved by the sanitizer (core/settings.ts).
 */

import type { ThinkingLevel } from "@earendil-works/pi-agent-core";
import { GRAPH_CONTEXT_TOKENS_MAX, isHexColor, type ChatSettings } from "../core";
import type {
	AgentSettings,
	AppearanceSettings,
	BackgroundModelRole,
	GeneralSettings,
	GraphSettings,
	RoleModelOverride,
} from "../core/settings.ts";
import { BACKGROUND_MODEL_ROLES } from "../core/settings.ts";
import { TOGGLEABLE_TOOLS } from "../core/pending.ts";

/** Parsed-or-rejected — `ok: false` carries the 400's error message. */
export type SettingsBodyResult<T> =
	| { ok: true; settings: T }
	| { ok: false; error: string };

export function parseSettingsBody(body: unknown): SettingsBodyResult<ChatSettings> {
	if (!body || typeof body !== "object" || Array.isArray(body)) {
		return { ok: false, error: "Invalid JSON body" };
	}
	const raw = body as {
		model?: { provider?: unknown; id?: unknown };
		thinkingLevel?: unknown;
		graphContextTokens?: unknown;
	};
	const settings: ChatSettings = {};
	if (raw.model !== undefined) {
		if (
			typeof raw.model !== "object" ||
			raw.model === null ||
			typeof raw.model.provider !== "string" ||
			typeof raw.model.id !== "string"
		) {
			return { ok: false, error: "model must be {provider, id}" };
		}
		settings.model = { provider: raw.model.provider, id: raw.model.id };
	}
	if (raw.thinkingLevel !== undefined) {
		if (typeof raw.thinkingLevel !== "string") {
			return { ok: false, error: "thinkingLevel must be a string" };
		}
		settings.thinkingLevel = raw.thinkingLevel as ThinkingLevel;
	}
	// Graph context injection budget (vision-context-injection.md): integer
	// tokens, 0 (off) to GRAPH_CONTEXT_TOKENS_MAX, no silent clamping — the
	// slider is the only writer, and it only ever sends multiples of the step.
	if (raw.graphContextTokens !== undefined) {
		if (
			typeof raw.graphContextTokens !== "number" ||
			!Number.isInteger(raw.graphContextTokens) ||
			raw.graphContextTokens < 0 ||
			raw.graphContextTokens > GRAPH_CONTEXT_TOKENS_MAX
		) {
			return {
				ok: false,
				error: `graphContextTokens must be an integer between 0 and ${GRAPH_CONTEXT_TOKENS_MAX}`,
			};
		}
		settings.graphContextTokens = raw.graphContextTokens;
	}
	return { ok: true, settings };
}

// ─── Section parsers (settings-storage wave, 2026-09-19) ────────────────────
// One parser per settings.json section; the route maps the URL section to
// its parser via SETTINGS_SECTIONS below. Same discipline as
// parseSettingsBody: strict on every known field (a bad type/shape is a
// 400, never a silent clamp/drop), unknown keys dropped.

function asRecord(body: unknown): Record<string, unknown> | null {
	if (!body || typeof body !== "object" || Array.isArray(body)) return null;
	return body as Record<string, unknown>;
}

/** general: { autoUpdate?: boolean } */
export function parseGeneralSettingsBody(body: unknown): SettingsBodyResult<GeneralSettings> {
	const raw = asRecord(body);
	if (!raw) return { ok: false, error: "Invalid JSON body" };
	const settings: GeneralSettings = {};
	if (raw.autoUpdate !== undefined) {
		if (typeof raw.autoUpdate !== "boolean") {
			return { ok: false, error: "autoUpdate must be a boolean" };
		}
		settings.autoUpdate = raw.autoUpdate;
	}
	return { ok: true, settings };
}

/** agent.models: only the six known background roles; each override's
 *  fields mirror ChatSettings (model pair + independent thinkingLevel). */
function parseRoleOverride(value: unknown, role: string): { ok: true; override: RoleModelOverride } | { ok: false; error: string } {
	const raw = asRecord(value);
	if (!raw) return { ok: false, error: `${role} must be an object` };
	const override: RoleModelOverride = {};
	if (raw.model !== undefined) {
		if (
			typeof raw.model !== "object" ||
			raw.model === null ||
			typeof (raw.model as Record<string, unknown>).provider !== "string" ||
			typeof (raw.model as Record<string, unknown>).id !== "string"
		) {
			return { ok: false, error: `${role}.model must be {provider, id}` };
		}
		override.model = {
			provider: (raw.model as { provider: string }).provider,
			id: (raw.model as { id: string }).id,
		};
	}
	if (raw.thinkingLevel !== undefined) {
		if (typeof raw.thinkingLevel !== "string") {
			return { ok: false, error: `${role}.thinkingLevel must be a string` };
		}
		override.thinkingLevel = raw.thinkingLevel as ThinkingLevel;
	}
	return { ok: true, override };
}

/** A boolean map (tools / prompts switches): every value must be boolean. */
function parseBooleanMap(value: unknown, field: string): { map?: Record<string, boolean>; error?: string } {
	if (value === undefined) return {};
	const raw = asRecord(value);
	if (!raw) return { error: `${field} must be an object` };
	const out: Record<string, boolean> = {};
	for (const [key, entry] of Object.entries(raw)) {
		if (typeof entry !== "boolean") return { error: `${field}.${key} must be a boolean` };
		out[key] = entry;
	}
	return { map: out };
}

/** agent: { models?, tools?, prompts? } — model/thinking validity against
 *  the catalog is checked by the route (validateChatSettings discipline);
 *  prompt switch-on membership is checked by the route (needs the store). */
export function parseAgentSettingsBody(body: unknown): SettingsBodyResult<AgentSettings> {
	const raw = asRecord(body);
	if (!raw) return { ok: false, error: "Invalid JSON body" };
	const settings: AgentSettings = {};
	if (raw.models !== undefined) {
		const models = asRecord(raw.models);
		if (!models) return { ok: false, error: "models must be an object" };
		const known = BACKGROUND_MODEL_ROLES as readonly string[];
		const parsed: NonNullable<AgentSettings["models"]> = {};
		for (const [role, value] of Object.entries(models)) {
			if (!known.includes(role)) {
				return { ok: false, error: `unknown role "${role}" (supported: ${known.join(", ")})` };
			}
			const override = parseRoleOverride(value, role);
			if (!override.ok) return { ok: false, error: override.error };
			if (Object.keys(override.override).length) parsed[role as BackgroundModelRole] = override.override;
		}
		if (Object.keys(parsed).length) settings.models = parsed;
	}
	const tools = parseBooleanMap(raw.tools, "tools");
	if (tools.error) return { ok: false, error: tools.error };
	if (tools.map) {
		// Unknown tool keys are rejected at WRITE time (user decision
		// 2026-09-19): the delta is inert while unread, but once the bridge
		// honors it a persisted `quiz: false` would genuinely drop the quiz —
		// and the definitive list is the adjudicated job-tools-only set.
		// The read-side sanitizer stays lenient for forward-compat.
		const supported = TOGGLEABLE_TOOLS as readonly string[];
		for (const key of Object.keys(tools.map)) {
			if (!supported.includes(key)) {
				return { ok: false, error: `unknown tool "${key}" (supported: ${supported.join(", ")})` };
			}
		}
		settings.tools = tools.map;
	}
	const prompts = parseBooleanMap(raw.prompts, "prompts");
	if (prompts.error) return { ok: false, error: prompts.error };
	if (prompts.map) settings.prompts = prompts.map;
	if (raw.search !== undefined) {
		const search = asRecord(raw.search);
		if (!search) return { ok: false, error: "search must be an object" };
		if (search.engine !== undefined) {
			if (search.engine !== "tavily" && search.engine !== "brave") {
				return { ok: false, error: 'search.engine must be "tavily" or "brave"' };
			}
			settings.search = { engine: search.engine };
		}
	}
	return { ok: true, settings };
}

/** A hex-or-null color field (appearance colors): null = default. */
function parseHexOrNull(value: unknown, field: string): { color?: string | null; error?: string } {
	if (value === null) return { color: null };
	if (typeof value !== "string" || !isHexColor(value)) {
		return { error: `${field} must be a #hex color or null` };
	}
	return { color: value };
}

/** appearance: { mode?, background?, fontFamily?, proseFontSize?,
 *  sessionNameSerif?, mdRendering? } */
export function parseAppearanceSettingsBody(body: unknown): SettingsBodyResult<AppearanceSettings> {
	const raw = asRecord(body);
	if (!raw) return { ok: false, error: "Invalid JSON body" };
	const settings: AppearanceSettings = {};
	if (raw.mode !== undefined) {
		if (raw.mode !== "dark" && raw.mode !== "light") {
			return { ok: false, error: "mode must be \"dark\" or \"light\"" };
		}
		settings.mode = raw.mode;
	}
	if (raw.background !== undefined) {
		const parsed = parseHexOrNull(raw.background, "background");
		if (parsed.error) return { ok: false, error: parsed.error };
		settings.background = parsed.color ?? null;
	}
	if (raw.fontFamily !== undefined) {
		if (raw.fontFamily !== null && (typeof raw.fontFamily !== "string" || !raw.fontFamily.trim())) {
			return { ok: false, error: "fontFamily must be a non-empty string or null" };
		}
		settings.fontFamily = raw.fontFamily as string | null;
	}
	if (raw.proseFontSize !== undefined) {
		if (
			typeof raw.proseFontSize !== "number" ||
			!Number.isInteger(raw.proseFontSize) ||
			raw.proseFontSize < 12 ||
			raw.proseFontSize > 24
		) {
			return { ok: false, error: "proseFontSize must be an integer between 12 and 24" };
		}
		settings.proseFontSize = raw.proseFontSize;
	}
	if (raw.sessionNameSerif !== undefined) {
		if (typeof raw.sessionNameSerif !== "boolean") {
			return { ok: false, error: "sessionNameSerif must be a boolean" };
		}
		settings.sessionNameSerif = raw.sessionNameSerif;
	}
	if (raw.mdRendering !== undefined) {
		const md = asRecord(raw.mdRendering);
		if (!md) return { ok: false, error: "mdRendering must be an object" };
		const rendering: NonNullable<AppearanceSettings["mdRendering"]> = {};
		if (md.headingWeight !== undefined) {
			if (
				typeof md.headingWeight !== "number" ||
				!Number.isInteger(md.headingWeight) ||
				md.headingWeight < 100 ||
				md.headingWeight > 900
			) {
				return { ok: false, error: "mdRendering.headingWeight must be an integer between 100 and 900" };
			}
			rendering.headingWeight = md.headingWeight;
		}
		if (md.boldColor !== undefined) {
			const parsed = parseHexOrNull(md.boldColor, "mdRendering.boldColor");
			if (parsed.error) return { ok: false, error: parsed.error };
			rendering.boldColor = parsed.color ?? null;
		}
		if (md.italicColor !== undefined) {
			const parsed = parseHexOrNull(md.italicColor, "mdRendering.italicColor");
			if (parsed.error) return { ok: false, error: parsed.error };
			rendering.italicColor = parsed.color ?? null;
		}
		if (Object.keys(rendering).length) settings.mdRendering = rendering;
	}
	return { ok: true, settings };
}

/** graph: the four-rung ladder { enabled?, embedding?, clustering?, labeling? }. */
export function parseGraphSettingsBody(body: unknown): SettingsBodyResult<GraphSettings> {
	const raw = asRecord(body);
	if (!raw) return { ok: false, error: "Invalid JSON body" };
	const settings: GraphSettings = {};
	for (const key of ["enabled", "embedding", "clustering", "labeling"] as const) {
		if (raw[key] !== undefined) {
			if (typeof raw[key] !== "boolean") {
				return { ok: false, error: `${key} must be a boolean` };
			}
			settings[key] = raw[key];
		}
	}
	return { ok: true, settings };
}

/** The section→parser map for PUT /api/settings/[section] (the route also
 *  carries the special prompts sub-resource). */
export const SETTINGS_SECTIONS = {
	general: parseGeneralSettingsBody,
	chat: parseSettingsBody,
	agent: parseAgentSettingsBody,
	appearance: parseAppearanceSettingsBody,
	graph: parseGraphSettingsBody,
} as const;

export type SettingsSectionName = keyof typeof SETTINGS_SECTIONS;