use serde::{Deserialize, Serialize};
use std::fmt;

/// Which Qwen3-Embedding size to use.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Deserialize, Serialize)]
pub enum ModelSize {
    #[serde(rename = "0.6B")]
    S06,
    #[serde(rename = "2B")]
    S2,
    #[serde(rename = "4B")]
    S4,
}

impl ModelSize {
    /// HuggingFace GGUF repo id.
    pub fn repo_id(self) -> &'static str {
        match self {
            Self::S06 => "Qwen/Qwen3-Embedding-0.6B-GGUF",
            Self::S2 => "Qwen/Qwen3-Embedding-2B-GGUF",
            Self::S4 => "Qwen/Qwen3-Embedding-4B-GGUF",
        }
    }

    /// GGUF filename inside the repo (F16 quant).
    pub fn gguf_filename(self) -> &'static str {
        match self {
            Self::S06 => "Qwen3-Embedding-0.6B-f16.gguf",
            Self::S2 => "Qwen3-Embedding-2B-f16.gguf",
            Self::S4 => "Qwen3-Embedding-4B-f16.gguf",
        }
    }

    /// Human-readable label returned in API responses.
    pub fn label(self) -> &'static str {
        match self {
            Self::S06 => "qwen3-embedding-0.6B",
            Self::S2 => "qwen3-embedding-2B",
            Self::S4 => "qwen3-embedding-4B",
        }
    }
}

impl fmt::Display for ModelSize {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(self.label())
    }
}

/// Whether the input is a document (no prefix) or a query (instruction prefix).
#[derive(Debug, Clone, Copy, PartialEq, Eq, Deserialize, Serialize)]
#[serde(rename_all = "lowercase")]
pub enum InputKind {
    Document,
    Query,
}

/// JSON body for POST /embed.
#[derive(Debug, Deserialize)]
pub struct EmbedRequest {
    pub texts: Vec<String>,
    pub input_type: InputKind,
    /// Model size to use. Defaults to 0.6B if omitted.
    pub size: Option<ModelSize>,
}

/// JSON response for POST /embed.
#[derive(Debug, Serialize)]
pub struct EmbedResponse {
    pub vectors: Vec<Vec<f32>>,
    pub dim: usize,
    pub model: String,
}