export const FASTAPI_BASE_URL = '/fastapi/api/v1'

export type TrainingType = 'case_analysis' | 'diagnosis_treatment' | 'consultation'
export type TrainingMode = 'practice' | 'teaching'
export type ScoreType = 'percentage' | 'five_point'

export type PatientConfigPayload = {
	visit_environment: 'outpatient' | 'emergency' | 'ward'
	age_group: 'child' | 'youth' | 'middle_aged' | 'elderly'
	education_level: 'primary_or_below' | 'secondary' | 'higher'
	personality: 'calm' | 'anxious' | 'impatient' | 'cooperative' | 'suspicious'
}

export type CreateSessionPayload = {
	case_id: number
	training_type: TrainingType
	mode: TrainingMode
	score_type: ScoreType
	patient_config: PatientConfigPayload
}

export type SessionPatientConfig = {
	values: PatientConfigPayload
	labels: Record<keyof PatientConfigPayload, string>
}

export type TrainingSession = {
	session_id: number
	session_code: string
	status: string
	patient_opening: string
	patient_config: SessionPatientConfig
}

type ApiEnvelope<T> = {
	code: string
	message: string
	data: T
}

type StreamCallbacks = {
	onDelta: (delta: string) => void
	onDone?: (meta: Record<string, unknown>) => void
}

type HintStreamPayload = {
	last_user_message: string
	scope: 'current_conversation'
}

function readAccessToken() {
	const token = uni.getStorageSync('clinical-thinking-access-token')
	if (typeof token !== 'string' || !token.trim()) {
		throw new Error('登录已过期，请重新登录')
	}
	return token
}

function authHeaders(accept = 'application/json') {
	return {
		'Content-Type': 'application/json',
		Accept: accept,
		Authorization: `Bearer ${readAccessToken()}`,
		'X-Entry-Scene': 'vue_frontend'
	}
}

async function readError(response: Response) {
	const text = await response.text().catch(() => '')
	if (!text) return `请求失败（${response.status}）`
	try {
		const payload = JSON.parse(text) as Record<string, unknown>
		const message = payload.message || payload.detail || payload.error
		if (typeof message === 'string' && message.trim()) return message
	} catch {}
	return text
}

export async function createTrainingSession(payload: CreateSessionPayload) {
	const response = await fetch(`${FASTAPI_BASE_URL}/sessions`, {
		method: 'POST',
		headers: authHeaders(),
		body: JSON.stringify(payload)
	})

	if (!response.ok) {
		throw new Error(await readError(response))
	}

	const result = (await response.json()) as ApiEnvelope<TrainingSession>
	if (result.code !== 'OK' || !result.data?.session_id) {
		throw new Error(result.message || '新建会话失败')
	}
	return result.data
}

export async function streamSessionChat(
	sessionId: number,
	message: string,
	callbacks: StreamCallbacks,
	signal?: AbortSignal
) {
	const response = await fetch(`${FASTAPI_BASE_URL}/sessions/${sessionId}/chat/stream`, {
		method: 'POST',
		headers: authHeaders('text/event-stream'),
		body: JSON.stringify({ message }),
		signal
	})

	if (!response.ok || !response.body) {
		throw new Error(await readError(response))
	}

	const reader = response.body.getReader()
	const decoder = new TextDecoder()
	let buffer = ''
	let completed = false

	while (true) {
		const { value, done } = await reader.read()
		if (done) break

		buffer += decoder.decode(value, { stream: true })
		const blocks = buffer.split('\n\n')
		buffer = blocks.pop() || ''

		for (const block of blocks) {
			const event = block.match(/^event:\s*(.+)$/m)?.[1]
			const rawData = block.match(/^data:\s*(.+)$/m)?.[1]
			if (!event || !rawData) continue

			const data = JSON.parse(rawData) as Record<string, unknown>
			if (event === 'message_delta') {
				const delta = data.delta
				if (typeof delta === 'string') callbacks.onDelta(delta)
			} else if (event === 'message_done') {
				completed = true
				callbacks.onDone?.(data)
			} else if (event === 'error') {
				throw new Error(typeof data.message === 'string' ? data.message : 'AI 流式回复异常')
			}
		}
	}

	if (!completed) {
		throw new Error('AI 流式回复未正常结束，请重试')
	}
}

export async function streamSessionHint(
	sessionId: number,
	lastUserMessage: string,
	callbacks: StreamCallbacks,
	signal?: AbortSignal
) {
	const payload: HintStreamPayload = {
		last_user_message: lastUserMessage,
		scope: 'current_conversation'
	}
	const response = await fetch(`${FASTAPI_BASE_URL}/sessions/${sessionId}/hints/stream`, {
		method: 'POST',
		headers: authHeaders('text/event-stream'),
		body: JSON.stringify(payload),
		signal
	})

	if (!response.ok || !response.body) {
		throw new Error(await readError(response))
	}

	const reader = response.body.getReader()
	const decoder = new TextDecoder()
	let buffer = ''
	let completed = false

	while (true) {
		const { value, done } = await reader.read()
		if (done) break

		buffer += decoder.decode(value, { stream: true })
		const blocks = buffer.split('\n\n')
		buffer = blocks.pop() || ''

		for (const block of blocks) {
			const event = block.match(/^event:\s*(.+)$/m)?.[1]
			const rawData = block.match(/^data:\s*(.+)$/m)?.[1]
			if (!event || !rawData) continue

			const data = JSON.parse(rawData) as Record<string, unknown>
			if (event === 'hint_delta') {
				const delta = data.delta
				if (typeof delta === 'string') callbacks.onDelta(delta)
			} else if (event === 'hint_done') {
				completed = true
				callbacks.onDone?.(data)
			} else if (event === 'error') {
				throw new Error(typeof data.message === 'string' ? data.message : '练习提示生成失败，请稍后重试')
			}
		}
	}

	if (!completed) {
		throw new Error('练习提示未正常结束，请重试')
	}
}