-- trae 源适配器（trae-local-api 的 OpenAI 兼容代理）
-- trae-local-api 运行在 http://127.0.0.1:19900，接 Trae CN 账号的云资源。
-- 协议：OpenAI /v1/chat/completions
-- 特性：
--   - 排队：上游 busy 时排队，可能长时间无响应
--   - 非流式请求偶发返回 SSE 数据（upstream bug）
--   - 支持 thinking，由上游模型自动决定是否开启

local adapter = {}
adapter.name = "trae"
adapter.version = "1.0.0"
adapter.endpoint = "/v1/chat/completions"
adapter.headers = {}

function adapter.transform_request(raw_body)
    local ok, req = pcall(json.decode, raw_body)
    if not ok then return raw_body end
    req.disable_thinking = nil
    req.extra_body = nil
    if req.messages then
        for _, msg in ipairs(req.messages) do
            msg.reasoning_content = nil
        end
    end
    return json.encode(req)
end

function adapter.transform_response(raw_body)
    -- trae-local-api 偶发在非流式请求中返回 SSE 格式数据，
    -- 表现为多个 data: {...} 行或混合了 reasoning_chunk 等。
    -- 剥掉 data: 前缀，取最后一个完整的 JSON 块（通常是
    -- 最终的 stop chunk 或 usage chunk）。
    local use_json = raw_body
    if raw_body:match("^data:") or raw_body:match("\ndata:") then
        -- 取最后一个 data: 行的 JSON
        local last = nil
        for line in raw_body:gmatch("data: ([^\n\r]+)") do
            local trimmed = line:match("^%s*(.-)%s*$")
            if trimmed and trimmed ~= "[DONE]" then
                local ok2, obj = pcall(json.decode, trimmed)
                if ok2 and type(obj) == "table" then
                    last = obj
                end
            end
        end
        if last then
            use_json = json.encode(last)
        end
        -- 如果解析失败，回退到原始 body
    end

    local ok, resp = pcall(json.decode, use_json)
    if not ok or resp == nil then return raw_body end

    local unified = {
        content = "",
        finish_reason = "",
        token_usage = { prompt = 0, completion = 0, total = 0 }
    }

    if type(resp.usage) == "table" then
        unified.token_usage.prompt = resp.usage.prompt_tokens or 0
        unified.token_usage.completion = resp.usage.completion_tokens or 0
        unified.token_usage.total = resp.usage.total_tokens or 0
    end

    if type(resp.choices) == "table" and #resp.choices > 0 then
        local ch = resp.choices[1]
        if type(ch.message) == "table" then
            unified.content = ch.message.content or ""
            if ch.message.reasoning_content then
                unified.reasoning_content = ch.message.reasoning_content
            end
            if type(ch.message.tool_calls) == "table" then
                local tcs = {}
                for _, tc in ipairs(ch.message.tool_calls) do
                    local args_ok, args = pcall(json.decode, tc["function"].arguments)
                    if not args_ok then args = {} end
                    table.insert(tcs, {
                        id = tc.id,
                        type = tc.type or "function",
                        name = tc["function"].name,
                        arguments = args
                    })
                end
                unified.tool_calls = tcs
            end
        end
        unified.finish_reason = ch.finish_reason or ""
    end

    return json.encode(unified)
end

function adapter.transform_stream_chunk(raw_chunk)
    local ok, chunk = pcall(json.decode, raw_chunk)
    if not ok then return "" end

    local uses = nil
    if type(chunk.usage) == "table" then
        uses = {
            prompt = chunk.usage.prompt_tokens or chunk.usage.prompt or 0,
            completion = chunk.usage.completion_tokens or chunk.usage.completion or 0,
            total = chunk.usage.total_tokens or chunk.usage.total or 0,
        }
        if type(chunk.usage.prompt_tokens_details) == "table" and chunk.usage.prompt_tokens_details.cached_tokens ~= nil then
            uses.prompt_tokens_details = { cached_tokens = chunk.usage.prompt_tokens_details.cached_tokens }
        elseif (chunk.usage.prompt_cache_hit_tokens or 0) > 0 then
            uses.prompt_cache_hit_tokens = chunk.usage.prompt_cache_hit_tokens
            uses.prompt_cache_miss_tokens = chunk.usage.prompt_cache_miss_tokens or 0
            uses.prompt_tokens_details = { cached_tokens = chunk.usage.prompt_cache_hit_tokens }
        end
    end

    if not chunk.choices or #chunk.choices == 0 then
        if uses ~= nil then
            return json.encode({ usage = uses, done = false })
        end
        return ""
    end
    local delta = chunk.choices[1].delta or {}
    local fr = chunk.choices[1].finish_reason

    local finish = (type(fr) == "string" and fr ~= "") and fr or nil

    local unified = {
        content = delta.content or "",
        done = (finish ~= nil)
    }
    if finish then
        unified.finish_reason = finish
    end
    if uses ~= nil then
        unified.usage = uses
    end
    if delta.reasoning_content then
        unified.reasoning_content = delta.reasoning_content
    end
    if delta.tool_calls then
        unified.tool_calls = delta.tool_calls
    end
    return json.encode(unified)
end

function adapter.transform_error(status, body)
    local ok, resp = pcall(json.decode, body)
    if not ok or type(resp) ~= "table" then
        -- Non-JSON body: extract title from HTML or first line
        local title = string.match(body or "", "<title>(.-)</title>")
        if title and title ~= "" then return title end
        local line = string.match(body or "", "^%s*([^\r\n]+)")
        if line and line ~= "" and not string.match(line, "^<") then
            return string.sub(line, 1, 200)
        end
        return nil
    end
    local e = resp.error
    if type(e) == "table" and type(e.message) == "string" then
        -- trae quota / rate limit annotations
        if e.code then
            return tostring(e.code) .. ": " .. e.message
        end
        return e.message
    end
    if type(e) == "string" then return e end
    if type(resp.message) == "string" and resp.message ~= "" then
        if resp.code ~= nil then
            return tostring(resp.code) .. ": " .. resp.message
        end
        return resp.message
    end
    return nil
end

return adapter