local fn = vim.fn

local curl = require("plenary.curl")

local Utils = require("avante.utils")
local Config = require("avante.config")
local Tiktoken = require("avante.tiktoken")

---@class avante.AiBot
local M = {}

local system_prompt = [[
You are an excellent programming expert.
]]

local base_user_prompt = [[
Your primary task is to suggest code modifications with precise line number ranges. Follow these instructions meticulously:

1. Carefully analyze the original code, paying close attention to its structure and line numbers. Line numbers start from 1 and include ALL lines, even empty ones.

2. When suggesting modifications:
   a. Use the language in the question to reply. If there are non-English parts in the question, use the language of those parts.
   b. Explain why the change is necessary or beneficial.
   c. Provide the exact code snippet to be replaced using this format:

Replace lines: {{start_line}}-{{end_line}}
```{{language}}
{{suggested_code}}
```

3. Crucial guidelines for line numbers:
   - The range {{start_line}}-{{end_line}} is INCLUSIVE. Both start_line and end_line are included in the replacement.
   - Count EVERY line, including empty lines, comments, and the LAST line of the file.
   - For single-line changes, use the same number for start and end lines.
   - For multi-line changes, ensure the range covers ALL affected lines, from the very first to the very last.
   - Include the entire block (e.g., complete function) when modifying structured code.
   - Pay special attention to the start_line, ensuring it's not omitted or incorrectly set.
   - Double-check that your start_line is correct, especially for changes at the beginning of the file.
   - Also, be careful with the end_line, especially when it's the last line of the file.
   - Double-check that your line numbers align perfectly with the original code structure.

4. Context and verification:
   - Show 1-2 unchanged lines before and after each modification as context.
   - These context lines are NOT included in the replacement range.
   - After each suggestion, recount the lines to verify the accuracy of your line numbers.
   - Double-check that both the start_line and end_line are correct for each modification.
   - Verify that your suggested changes align perfectly with the original code structure.

5. Final check:
   - Review all suggestions, ensuring each line number is correct, especially the start_line and end_line.
   - Pay extra attention to the start_line of each modification, ensuring it hasn't shifted down.
   - Confirm that no unrelated code is accidentally modified or deleted.
   - Verify that the start_line and end_line correctly include all intended lines for replacement.
   - If a modification involves the first or last line of the file, explicitly state this in your explanation.
   - Perform a final alignment check to ensure your line numbers haven't shifted, especially the start_line.
   - Double-check that your line numbers align perfectly with the original code structure.
   - Do not show the content after these modifications.

Remember: Accurate line numbers are CRITICAL. The range start_line to end_line must include ALL lines to be replaced, from the very first to the very last. Double-check every range before finalizing your response, paying special attention to the start_line to ensure it hasn't shifted down. Ensure that your line numbers perfectly match the original code structure without any overall shift.
]]

local function call_claude_api_stream(question, code_lang, code_content, selected_code_content, on_chunk, on_complete)
  local api_key = os.getenv("ANTHROPIC_API_KEY")
  if not api_key then
    error("ANTHROPIC_API_KEY environment variable is not set")
  end

  local tokens = Config.claude.max_tokens
  local headers = {
    ["Content-Type"] = "application/json",
    ["x-api-key"] = api_key,
    ["anthropic-version"] = "2023-06-01",
    ["anthropic-beta"] = "prompt-caching-2024-07-31",
  }

  local code_prompt_obj = {
    type = "text",
    text = string.format("<code>```%s\n%s```</code>", code_lang, code_content),
  }

  if Tiktoken.count(code_prompt_obj.text) > 1024 then
    code_prompt_obj.cache_control = { type = "ephemeral" }
  end

  if selected_code_content then
    code_prompt_obj.text = string.format("<code_context>```%s\n%s```</code_context>", code_lang, code_content)
  end

  local message_content = {
    code_prompt_obj,
  }

  if selected_code_content then
    local selected_code_obj = {
      type = "text",
      text = string.format("<code>```%s\n%s```</code>", code_lang, selected_code_content),
    }

    if Tiktoken.count(selected_code_obj.text) > 1024 then
      selected_code_obj.cache_control = { type = "ephemeral" }
    end

    table.insert(message_content, selected_code_obj)
  end

  table.insert(message_content, {
    type = "text",
    text = string.format("<question>%s</question>", question),
  })

  local user_prompt = base_user_prompt

  local user_prompt_obj = {
    type = "text",
    text = user_prompt,
  }

  if Tiktoken.count(user_prompt_obj.text) > 1024 then
    user_prompt_obj.cache_control = { type = "ephemeral" }
  end

  table.insert(message_content, user_prompt_obj)

  local body = {
    model = Config.claude.model,
    system = system_prompt,
    messages = {
      {
        role = "user",
        content = message_content,
      },
    },
    stream = true,
    temperature = Config.claude.temperature,
    max_tokens = tokens,
  }

  local url = Utils.trim_suffix(Config.claude.endpoint, "/") .. "/v1/messages"

  -- print("Sending request to Claude API...")

  curl.post(url, {
    ---@diagnostic disable-next-line: unused-local
    stream = function(err, data, job)
      if err then
        on_complete(err)
        return
      end
      if not data then
        return
      end
      for _, line in ipairs(vim.split(data, "\n")) do
        if line:sub(1, 6) ~= "data: " then
          return
        end
        vim.schedule(function()
          local success, parsed = pcall(fn.json_decode, line:sub(7))
          if not success then
            error("Error: failed to parse json: " .. parsed)
            return
          end
          if parsed and parsed.type == "content_block_delta" then
            on_chunk(parsed.delta.text)
          elseif parsed and parsed.type == "message_stop" then
            -- Stream request completed
            on_complete(nil)
          elseif parsed and parsed.type == "error" then
            -- Stream request completed
            on_complete(parsed)
          end
        end)
      end
    end,
    headers = headers,
    body = fn.json_encode(body),
  })
end

local function call_openai_api_stream(question, code_lang, code_content, selected_code_content, on_chunk, on_complete)
  local api_key = os.getenv("OPENAI_API_KEY")
  if not api_key and Config.provider == "openai" then
    error("OPENAI_API_KEY environment variable is not set")
  end

  local user_prompt = base_user_prompt
    .. "\n\nCODE:\n"
    .. "```"
    .. code_lang
    .. "\n"
    .. code_content
    .. "\n```"
    .. "\n\nQUESTION:\n"
    .. question

  if selected_code_content then
    user_prompt = base_user_prompt
      .. "\n\nCODE CONTEXT:\n"
      .. "```"
      .. code_lang
      .. "\n"
      .. code_content
      .. "\n```"
      .. "\n\nCODE:\n"
      .. "```"
      .. code_lang
      .. "\n"
      .. selected_code_content
      .. "\n```"
      .. "\n\nQUESTION:\n"
      .. question
  end

  local url, headers, body
  if Config.provider == "azure" then
    api_key = os.getenv("AZURE_OPENAI_API_KEY") or os.getenv("OPENAI_API_KEY")
    if not api_key then
      error("Azure OpenAI API key is not set. Please set AZURE_OPENAI_API_KEY or OPENAI_API_KEY environment variable.")
    end
    url = Config.azure.endpoint
      .. "/openai/deployments/"
      .. Config.azure.deployment
      .. "/chat/completions?api-version="
      .. Config.azure.api_version
    headers = {
      ["Content-Type"] = "application/json",
      ["api-key"] = api_key,
    }
    body = {
      messages = {
        { role = "system", content = system_prompt },
        { role = "user", content = user_prompt },
      },
      temperature = Config.azure.temperature,
      max_tokens = Config.azure.max_tokens,
      stream = true,
    }
  else
    url = Utils.trim_suffix(Config.openai.endpoint, "/") .. "/v1/chat/completions"
    headers = {
      ["Content-Type"] = "application/json",
      ["Authorization"] = "Bearer " .. api_key,
    }
    body = {
      model = Config.openai.model,
      messages = {
        { role = "system", content = system_prompt },
        { role = "user", content = user_prompt },
      },
      temperature = Config.openai.temperature,
      max_tokens = Config.openai.max_tokens,
      stream = true,
    }
  end

  -- print("Sending request to " .. (config.get().provider == "azure" and "Azure OpenAI" or "OpenAI") .. " API...")

  curl.post(url, {
    ---@diagnostic disable-next-line: unused-local
    stream = function(err, data, job)
      if err then
        on_complete(err)
        return
      end
      if not data then
        return
      end
      for _, line in ipairs(vim.split(data, "\n")) do
        if line:sub(1, 6) ~= "data: " then
          return
        end
        vim.schedule(function()
          local piece = line:sub(7)
          local success, parsed = pcall(fn.json_decode, piece)
          if not success then
            if piece == "[DONE]" then
              on_complete(nil)
              return
            end
            error("Error: failed to parse json: " .. parsed)
            return
          end
          if parsed and parsed.choices and parsed.choices[1] then
            local choice = parsed.choices[1]
            if choice.finish_reason == "stop" then
              on_complete(nil)
            elseif choice.delta and choice.delta.content then
              on_chunk(choice.delta.content)
            end
          end
        end)
      end
    end,
    headers = headers,
    body = fn.json_encode(body),
  })
end

---@param question string
---@param code_lang string
---@param code_content string
---@param selected_content_content string | nil
---@param on_chunk fun(chunk: string): any
---@param on_complete fun(err: string|nil): any
function M.call_ai_api_stream(question, code_lang, code_content, selected_content_content, on_chunk, on_complete)
  if Config.provider == "openai" or Config.provider == "azure" then
    call_openai_api_stream(question, code_lang, code_content, selected_content_content, on_chunk, on_complete)
  elseif Config.provider == "claude" then
    call_claude_api_stream(question, code_lang, code_content, selected_content_content, on_chunk, on_complete)
  end
end

return M