local adapter = {}

adapter.name = "buddy"
adapter.version = "1.0.0"
adapter.endpoint = "/chat/completions"
adapter.headers = {}

-- Claude-behind-OpenAI upstreams (tabitoken, 扇贝, …) convert /chat/completions
-- to the Anthropic Messages API internally, so they inherit Anthropic's
-- tool id rule: ^[a-zA-Z0-9_-]{1,64}$, enforced by rejecting the WHOLE request
-- with "Invalid tool use format" / "tool_use.id: String should match pattern".
-- Plain OpenAI has no such rule, so an OpenAI-compatible model can mint an id
-- like "bash:0" (observed from moonshotai/kimi-k3). In a fan-out router that id
-- is replayed to every other source, so one such id kills every Claude slot at
-- once and an AUTO request falls through all tiers.
--
-- safe_tool_id is pure and deterministic, so a tool_calls entry and its
-- matching tool_call_id are rewritten identically within one request. A
-- rewritten id keeps an 8-hex digest of the ORIGINAL id, without which two
-- distinct ids could collapse into one ("a:b" and "a_b") and become an
-- unpaired/duplicate tool call. Already-legal ids are returned untouched, so
-- well-behaved traffic is byte-identical to before.
-- (anthropic.lua carries the same helper; Lua adapters have no shared prelude.)
local TOOL_ID_MAX = 64

local function safe_tool_id(id)
    if type(id) ~= "string" or id == "" then return id end
    local clean = string.gsub(id, "[^A-Za-z0-9_-]", "_")
    if clean == id and #clean <= TOOL_ID_MAX then
        return clean
    end
    local digest = string.sub(sha256_hex(id), 1, 8)
    local keep = TOOL_ID_MAX - #digest - 1
    if #clean > keep then clean = string.sub(clean, 1, keep) end
    return clean .. "_" .. digest
end

-- 需要补 reasoning_effort 的模型 → 补哪个档位。
--
-- 唯一出处：参考 product.ts:237 声明 glm-5.1 的 reasoningEfforts 只有 ['medium']。
-- 但实测**任何非空档位都被接受**，故这里取 medium（与参考声明一致）。
local NEED_EFFORT = {
    ["glm-5.1"] = "medium",
}

-- OpenAI /chat/completions format (pass-through, strip provider-specific fields)
function adapter.transform_request(raw_body)
    local ok, req = pcall(json.decode, raw_body)
    if not ok then return raw_body end
    -- The gateway's private control fields are GONE from the body (v2): the
    -- neutral `thinking` field carries that intent and each adapter maps it in
    -- its own protocol terms. These upstreams have no thinking switch at all,
    -- so the field is simply dropped here — which is what the nil-ing below
    -- used to do, except the field being dropped is no longer the kernel's
    -- private one.
    req.thinking = nil
    req.extra_body = nil
    -- ★★ buddy（腾讯 CodeBuddy）上游**只支持流式**：body.stream=false 会被
    --    400 拒绝（实测 2026-10-19）：
    --      11101: Non-stream chat request is currently not supported
    --    与 Accept: text/event-stream 头无关（头早已在发），判据是 body。
    --    故强制 stream=true，非流式请求由内核的"客户端要非流式、上游回流式"
    --    路径消化（transform_response 需能聚合 SSE，见下）。
    req.stream = true
    -- ★★ buddy 的 glm-5.1 **要求请求体里有非空的 reasoning_effort**，
    --    否则上游回 400：
    --      {"code":11150,"msg":"the reasoning effort value is not supported
    --       by the current model"}
    --    实测（2026-10-16，逐字对照实验）：
    --      glm-5.1 裸（无该字段）             → 400 11150  ✗
    --      glm-5.1 + reasoning_effort:medium  → 200        ✓
    --      glm-5.1 空串                       → 400 11150  ✗
    --      任何**非空**档位均可（low/medium/high/xhigh/max/minimal 逐个 200）
    --    而其余 15 个 buddy 模型裸跑全 200（多带该字段也无害）—— 即这是
    --    glm-5.1 **独有**的要求。
    -- ⚠️ 只对**已实测需要**的模型补（而不是一律补）：一律补会把"某个模型的
    --    特殊要求"扩成"全平台行为"，将来上游若对某些模型收紧就会一次性弄坏
    --    所有模型。
    if NEED_EFFORT[req.model or ""] and
       not (type(req.reasoning_effort) == "string" and req.reasoning_effort ~= "") and
       req.reasoning_effort == nil then
        req.reasoning_effort = NEED_EFFORT[req.model]
    end
    if req.messages then
        for _, msg in ipairs(req.messages) do
            msg.reasoning_content = nil
            if msg.tool_call_id ~= nil then
                msg.tool_call_id = safe_tool_id(msg.tool_call_id)
            end
            if type(msg.tool_calls) == "table" then
                for _, tc in ipairs(msg.tool_calls) do
                    if type(tc) == "table" and tc.id ~= nil then
                        tc.id = safe_tool_id(tc.id)
                    end
                end
            end
        end
    end
    return json.encode(req)
end

-- aggregate_sse(raw)：把上游 SSE（data: 行流）聚合成一个非流式 OpenAI 响应。
-- 强制 stream=true 后，内核的非流式路径会在这里收到完整 SSE 原文——必须聚合，
-- 否则 json.decode 失败原样透传，Go 侧 unmarshal 报 invalid character 'd'。
-- 聚合 content / reasoning_content / tool_calls（按 index 拼接分片）/
-- finish_reason / usage；无可解析帧时返回 nil（调用方回退原样）。
local function aggregate_sse(raw)
    local content, reasoning = {}, {}
    local finish, usage, id, model, created = nil, nil, nil, nil, nil
    local tools_by_index = {}
    local seen = false
    for line in (raw .. "\n"):gmatch("([^\n]*)\n") do
        local s = line:gsub("^%s+", ""):gsub("%s+$", "")
        if s:sub(1, 5) == "data:" then
            local payload = s:sub(6):gsub("^%s+", "")
            if payload ~= "" and payload ~= "[DONE]" then
                local ok, d = pcall(json.decode, payload)
                if ok and type(d) == "table" then
                    seen = true
                    id = id or d.id
                    model = model or d.model
                    created = created or d.created
                    if type(d.usage) == "table" then usage = d.usage end
                    local ch = d.choices and d.choices[1]
                    if type(ch) == "table" then
                        if type(ch.finish_reason) == "string" and ch.finish_reason ~= "" then
                            finish = ch.finish_reason
                        end
                        local dl = ch.delta
                        if type(dl) == "table" then
                            if type(dl.content) == "string" then content[#content + 1] = dl.content end
                            if type(dl.reasoning_content) == "string" then
                                reasoning[#reasoning + 1] = dl.reasoning_content
                            end
                            if type(dl.tool_calls) == "table" then
                                for _, tc in ipairs(dl.tool_calls) do
                                    if type(tc) == "table" and tc.index ~= nil then
                                        local slot = tools_by_index[tc.index]
                                        if slot == nil then
                                            slot = { id = tc.id, type = tc.type or "function",
                                                ["function"] = { name = "", arguments = "" } }
                                            tools_by_index[tc.index] = slot
                                        end
                                        if tc.id then slot.id = tc.id end
                                        local fn = tc["function"]
                                        if type(fn) == "table" then
                                            if fn.name then slot["function"].name = slot["function"].name .. fn.name end
                                            if fn.arguments then slot["function"].arguments = slot["function"].arguments .. fn.arguments end
                                        end
                                    end
                                end
                            end
                        end
                    end
                end
            end
        end
    end
    if not seen then return nil end
    local msg = { role = "assistant", content = table.concat(content) }
    local rc = table.concat(reasoning)
    if rc ~= "" then msg.reasoning_content = rc end
    local ordered = {}
    for i = 0, 63 do
        if tools_by_index[i] then ordered[#ordered + 1] = tools_by_index[i] end
    end
    if #ordered > 0 then msg.tool_calls = ordered end
    local out = {
        id = id or "", object = "chat.completion", created = created or 0,
        model = model or "",
        choices = { { index = 0, message = msg,
            finish_reason = (finish and finish ~= "") and finish or "stop" } },
    }
    if usage then out.usage = usage end
    local ok2, enc = pcall(json.encode, out)
    if not ok2 then return nil end
    return enc
end

function adapter.transform_response(raw_body)
    -- 上游只会回流式（transform_request 强制 stream=true）。客户端要非流式时
    -- 内核把完整 SSE 原文交到这里，先聚合再走统一转换。
    if type(raw_body) == "string"
        and (raw_body:match("^%s*data:") or raw_body:match("[\r\n]data:")) then
        local aggregated = aggregate_sse(raw_body)
        if aggregated ~= nil then raw_body = aggregated end
    end
    -- 非流式 OpenAI 响应 → 统一信封。此前在 openai/groq/kimicode/mistral/github
    -- 五个适配器里**逐字节相同**（各 2206B，diff 为空），已抽到共享前导。
    return __prelude.openai_response(raw_body)
end

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

    -- OpenAI-style streams may attach usage to a chunk with empty choices
    -- (the final usage chunk). Keys must match Go's TokenUsage json tags
    -- (prompt/completion/total); the gateway re-emits standard *_tokens.
    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
            -- usage-only chunk is not a content/finish signal; the gateway
            -- emits its own terminal stop chunk and merges this usage.
            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 type(delta.tool_calls) == "table" and #delta.tool_calls > 0 then
        -- Do not serialize an empty Lua table as JSON `{}`. That shape is
        -- neither an OpenAI tool-call array nor an omitted field, and several
        -- agent clients reject it on the final chunk.
        for _, tc in ipairs(delta.tool_calls) do
            if type(tc) == "table" and tc.id ~= nil then
                tc.id = safe_tool_id(tc.id)
            end
        end
        unified.tool_calls = delta.tool_calls
    end
    return json.encode(unified)
end

-- 错误收敛：标准 OpenAI 信封 {error:{message,...}}
function adapter.transform_error(status, body)
    -- OpenAI 风格错误体抽消息。此前在 deepseek/github/groq/kimicode/
    -- openai/sensenova 六个适配器里逐字节相同（各 293B），已抽到共享前导。
    return __prelude.openai_error(status, body)
end


-- ★ build_headers：buddy 要求客户端身份头 + 流式的 Accept。
--
-- 实测（2026-10-16）：不发 `Accept: text/event-stream` 时上游接受请求（200）
-- 但只回一帧空内容（completion_tokens=0），既不报错也不产出正文 —— 表现是
-- "模型不回答"，极易误判成模型坏了或额度不足。
-- 参考 buddy-adapter.ts 的 send() 固定发该头。
--
-- 身份头照参考 credentialRequestHeaders + CODEBUDDY 产品配置：
-- X-Domain 用产品域（不用凭据里的 domain 快照，那是登录时的区域，
-- 跨产品迁移后会指错区）；X-Product 是**部署类型**（SaaS）；X-Product-Code
-- 是产品码（codebuddy）。
function adapter.build_headers(meta)
    local h = {
        ["Accept"] = "text/event-stream",
        ["Content-Type"] = "application/json",
        ["X-Domain"] = "copilot.tencent.com",
        ["X-Product"] = "SaaS",
        ["X-Product-Code"] = "codebuddy",
        ["User-Agent"] = "CodeBuddyIDE/1.106.1",
    }
    -- Authorization 由内核在 buildHeaders 之后补（值为源的 api_key）——
    -- 这里显式给出同一份，保证与其它 buddy 请求形态一致。
    if type(meta) == "table" and type(meta.api_key) == "string" and meta.api_key ~= "" then
        h["Authorization"] = "Bearer " .. meta.api_key
    end
    return h
end

return adapter