use serde::Deserialize;
use serde::Serialize;
use serde_json::Value as JsonValue;

use crate::PUBLIC_TOOL_NAME;

const MAX_JS_SAFE_INTEGER: u64 = (1_u64 << 53) - 1;
const CODE_MODE_ONLY_PREFACE: &str =
    "Use `exec/wait` tool to run all other tools, do not attempt to use any other tools directly";
const EXEC_DESCRIPTION_TEMPLATE: &str = r#"Run JavaScript code to orchestrate/compose tool calls
- Evaluates the provided JavaScript code in a fresh V8 isolate as an async module.
- All nested tools are available on the global `tools` object, for example `await tools.exec_command(...)`. Tool names are exposed as normalized JavaScript identifiers, for example `await tools.mcp__ologs__get_profile(...)`.
- Nested tool methods take either a string or an object as their input argument.
- Nested tools return either an object or a string, based on the description.
- Runs raw JavaScript -- no Node, no file system, no network access, no console.
- Accepts raw JavaScript source text, not JSON, quoted strings, or markdown code fences.
- You may optionally start the tool input with a first-line pragma like `// @exec: {"yield_time_ms": 10000, "max_output_tokens": 1000}`.
- `yield_time_ms` asks `exec` to yield early after that many milliseconds if the script is still running.
- `max_output_tokens` sets the token budget for direct `exec` results. By default the result is truncated to 10000 tokens.
- When the JS code is fully evaluated, the isolate's lifetime ends and unawaited promises are silently discarded.

- Global helpers:
- `exit()`: Immediately ends the current script successfully (like an early return from the top level).
- `text(value: string | number | boolean | undefined | null)`: Appends a text item. Non-string values are stringified with `JSON.stringify(...)` when possible.
- `image(imageUrlOrItem: string | { image_url: string; detail?: "auto" | "low" | "high" | "original" | null })`: Appends an image item. `image_url` can be an HTTPS URL or a base64-encoded `data:` URL.
- `store(key: string, value: any)`: stores a serializable value under a string key for later `exec` calls in the same session.
- `load(key: string)`: returns the stored value for a string key, or `undefined` if it is missing.
- `notify(value: string | number | boolean | undefined | null)`: immediately injects an extra `custom_tool_call_output` for the current `exec` call. Values are stringified like `text(...)`.
- `ALL_TOOLS`: metadata for the enabled nested tools as `{ name, description }` entries.
- `yield_control()`: yields the accumulated output to the model immediately while the script keeps running."#;
const WAIT_DESCRIPTION_TEMPLATE: &str = r#"- Use `wait` only after `exec` returns `Script running with cell ID ...`.
- `cell_id` identifies the running `exec` cell to resume.
- `yield_time_ms` controls how long to wait for more output before yielding again. If omitted, `wait` uses its default wait timeout.
- `max_tokens` limits how much new output this wait call returns.
- `terminate: true` stops the running cell instead of waiting for more output.
- `wait` returns only the new output since the last yield, or the final completion or termination result for that cell.
- If the cell is still running, `wait` may yield again with the same `cell_id`.
- If the cell has already finished, `wait` returns the completed result and closes the cell."#;

pub const CODE_MODE_PRAGMA_PREFIX: &str = "// @exec:";

#[derive(Clone, Copy, Debug, Deserialize, Eq, PartialEq, Serialize)]
#[serde(rename_all = "snake_case")]
pub enum CodeModeToolKind {
    Function,
    Freeform,
}

#[derive(Clone, Debug, PartialEq)]
pub struct ToolDefinition {
    pub name: String,
    pub description: String,
    pub kind: CodeModeToolKind,
    pub input_schema: Option<JsonValue>,
    pub output_schema: Option<JsonValue>,
}

#[derive(Debug, Default, Deserialize, PartialEq, Eq)]
#[serde(deny_unknown_fields)]
struct CodeModeExecPragma {
    #[serde(default)]
    yield_time_ms: Option<u64>,
    #[serde(default)]
    max_output_tokens: Option<usize>,
}

#[derive(Debug, PartialEq, Eq)]
pub struct ParsedExecSource {
    pub code: String,
    pub yield_time_ms: Option<u64>,
    pub max_output_tokens: Option<usize>,
}

pub fn parse_exec_source(input: &str) -> Result<ParsedExecSource, String> {
    if input.trim().is_empty() {
        return Err(
            "exec expects raw JavaScript source text (non-empty). Provide JS only, optionally with first-line `// @exec: {\"yield_time_ms\": 10000, \"max_output_tokens\": 1000}`.".to_string(),
        );
    }

    let mut args = ParsedExecSource {
        code: input.to_string(),
        yield_time_ms: None,
        max_output_tokens: None,
    };

    let mut lines = input.splitn(2, '\n');
    let first_line = lines.next().unwrap_or_default();
    let rest = lines.next().unwrap_or_default();
    let trimmed = first_line.trim_start();
    let Some(pragma) = trimmed.strip_prefix(CODE_MODE_PRAGMA_PREFIX) else {
        return Ok(args);
    };

    if rest.trim().is_empty() {
        return Err(
            "exec pragma must be followed by JavaScript source on subsequent lines".to_string(),
        );
    }

    let directive = pragma.trim();
    if directive.is_empty() {
        return Err(
            "exec pragma must be a JSON object with supported fields `yield_time_ms` and `max_output_tokens`"
                .to_string(),
        );
    }

    let value: serde_json::Value = serde_json::from_str(directive).map_err(|err| {
        format!(
            "exec pragma must be valid JSON with supported fields `yield_time_ms` and `max_output_tokens`: {err}"
        )
    })?;
    let object = value.as_object().ok_or_else(|| {
        "exec pragma must be a JSON object with supported fields `yield_time_ms` and `max_output_tokens`"
            .to_string()
    })?;
    for key in object.keys() {
        match key.as_str() {
            "yield_time_ms" | "max_output_tokens" => {}
            _ => {
                return Err(format!(
                    "exec pragma only supports `yield_time_ms` and `max_output_tokens`; got `{key}`"
                ));
            }
        }
    }

    let pragma: CodeModeExecPragma = serde_json::from_value(value).map_err(|err| {
        format!(
            "exec pragma fields `yield_time_ms` and `max_output_tokens` must be non-negative safe integers: {err}"
        )
    })?;
    if pragma
        .yield_time_ms
        .is_some_and(|yield_time_ms| yield_time_ms > MAX_JS_SAFE_INTEGER)
    {
        return Err(
            "exec pragma field `yield_time_ms` must be a non-negative safe integer".to_string(),
        );
    }
    if pragma.max_output_tokens.is_some_and(|max_output_tokens| {
        u64::try_from(max_output_tokens)
            .map(|max_output_tokens| max_output_tokens > MAX_JS_SAFE_INTEGER)
            .unwrap_or(true)
    }) {
        return Err(
            "exec pragma field `max_output_tokens` must be a non-negative safe integer".to_string(),
        );
    }

    args.code = rest.to_string();
    args.yield_time_ms = pragma.yield_time_ms;
    args.max_output_tokens = pragma.max_output_tokens;
    Ok(args)
}

pub fn is_code_mode_nested_tool(tool_name: &str) -> bool {
    tool_name != crate::PUBLIC_TOOL_NAME && tool_name != crate::WAIT_TOOL_NAME
}

pub fn build_exec_tool_description(
    enabled_tools: &[(String, String)],
    code_mode_only: bool,
) -> String {
    if !code_mode_only {
        return EXEC_DESCRIPTION_TEMPLATE.to_string();
    }

    let mut sections = vec![
        CODE_MODE_ONLY_PREFACE.to_string(),
        EXEC_DESCRIPTION_TEMPLATE.to_string(),
    ];

    if !enabled_tools.is_empty() {
        let nested_tool_reference = enabled_tools
            .iter()
            .map(|(name, nested_description)| {
                let global_name = normalize_code_mode_identifier(name);
                format!(
                    "### `{global_name}` (`{name}`)\n{}",
                    nested_description.trim()
                )
            })
            .collect::<Vec<_>>()
            .join("\n\n");
        sections.push(nested_tool_reference);
    }

    sections.join("\n\n")
}

pub fn build_wait_tool_description() -> &'static str {
    WAIT_DESCRIPTION_TEMPLATE
}

pub fn normalize_code_mode_identifier(tool_key: &str) -> String {
    let mut identifier = String::new();

    for (index, ch) in tool_key.chars().enumerate() {
        let is_valid = if index == 0 {
            ch == '_' || ch == '$' || ch.is_ascii_alphabetic()
        } else {
            ch == '_' || ch == '$' || ch.is_ascii_alphanumeric()
        };

        if is_valid {
            identifier.push(ch);
        } else {
            identifier.push('_');
        }
    }

    if identifier.is_empty() {
        "_".to_string()
    } else {
        identifier
    }
}

pub fn augment_tool_definition(mut definition: ToolDefinition) -> ToolDefinition {
    if definition.name != PUBLIC_TOOL_NAME {
        definition.description = append_code_mode_sample_for_definition(&definition);
    }
    definition
}

pub fn enabled_tool_metadata(definition: &ToolDefinition) -> EnabledToolMetadata {
    EnabledToolMetadata {
        tool_name: definition.name.clone(),
        global_name: normalize_code_mode_identifier(&definition.name),
        description: definition.description.clone(),
        kind: definition.kind,
    }
}

#[derive(Clone, Debug, Eq, PartialEq, Serialize)]
pub struct EnabledToolMetadata {
    pub tool_name: String,
    pub global_name: String,
    pub description: String,
    pub kind: CodeModeToolKind,
}

pub fn append_code_mode_sample(
    description: &str,
    tool_name: &str,
    input_name: &str,
    input_type: String,
    output_type: String,
) -> String {
    let declaration = format!(
        "declare const tools: {{ {} }};",
        render_code_mode_tool_declaration(tool_name, input_name, input_type, output_type)
    );
    format!("{description}\n\nexec tool declaration:\n```ts\n{declaration}\n```")
}

fn append_code_mode_sample_for_definition(definition: &ToolDefinition) -> String {
    let input_name = match definition.kind {
        CodeModeToolKind::Function => "args",
        CodeModeToolKind::Freeform => "input",
    };
    let input_type = match definition.kind {
        CodeModeToolKind::Function => definition
            .input_schema
            .as_ref()
            .map(render_json_schema_to_typescript)
            .unwrap_or_else(|| "unknown".to_string()),
        CodeModeToolKind::Freeform => "string".to_string(),
    };
    let output_type = definition
        .output_schema
        .as_ref()
        .map(render_json_schema_to_typescript)
        .unwrap_or_else(|| "unknown".to_string());
    append_code_mode_sample(
        &definition.description,
        &definition.name,
        input_name,
        input_type,
        output_type,
    )
}

fn render_code_mode_tool_declaration(
    tool_name: &str,
    input_name: &str,
    input_type: String,
    output_type: String,
) -> String {
    let tool_name = normalize_code_mode_identifier(tool_name);
    format!("{tool_name}({input_name}: {input_type}): Promise<{output_type}>;")
}

pub fn render_json_schema_to_typescript(schema: &JsonValue) -> String {
    render_json_schema_to_typescript_inner(schema)
}

fn render_json_schema_to_typescript_inner(schema: &JsonValue) -> String {
    match schema {
        JsonValue::Bool(true) => "unknown".to_string(),
        JsonValue::Bool(false) => "never".to_string(),
        JsonValue::Object(map) => {
            if let Some(value) = map.get("const") {
                return render_json_schema_literal(value);
            }

            if let Some(values) = map.get("enum").and_then(JsonValue::as_array) {
                let rendered = values
                    .iter()
                    .map(render_json_schema_literal)
                    .collect::<Vec<_>>();
                if !rendered.is_empty() {
                    return rendered.join(" | ");
                }
            }

            for key in ["anyOf", "oneOf"] {
                if let Some(variants) = map.get(key).and_then(JsonValue::as_array) {
                    let rendered = variants
                        .iter()
                        .map(render_json_schema_to_typescript_inner)
                        .collect::<Vec<_>>();
                    if !rendered.is_empty() {
                        return rendered.join(" | ");
                    }
                }
            }

            if let Some(variants) = map.get("allOf").and_then(JsonValue::as_array) {
                let rendered = variants
                    .iter()
                    .map(render_json_schema_to_typescript_inner)
                    .collect::<Vec<_>>();
                if !rendered.is_empty() {
                    return rendered.join(" & ");
                }
            }

            if let Some(schema_type) = map.get("type") {
                if let Some(types) = schema_type.as_array() {
                    let rendered = types
                        .iter()
                        .filter_map(JsonValue::as_str)
                        .map(|schema_type| render_json_schema_type_keyword(map, schema_type))
                        .collect::<Vec<_>>();
                    if !rendered.is_empty() {
                        return rendered.join(" | ");
                    }
                }

                if let Some(schema_type) = schema_type.as_str() {
                    return render_json_schema_type_keyword(map, schema_type);
                }
            }

            if map.contains_key("properties")
                || map.contains_key("additionalProperties")
                || map.contains_key("required")
            {
                return render_json_schema_object(map);
            }

            if map.contains_key("items") || map.contains_key("prefixItems") {
                return render_json_schema_array(map);
            }

            "unknown".to_string()
        }
        _ => "unknown".to_string(),
    }
}

fn render_json_schema_type_keyword(
    map: &serde_json::Map<String, JsonValue>,
    schema_type: &str,
) -> String {
    match schema_type {
        "string" => "string".to_string(),
        "number" | "integer" => "number".to_string(),
        "boolean" => "boolean".to_string(),
        "null" => "null".to_string(),
        "array" => render_json_schema_array(map),
        "object" => render_json_schema_object(map),
        _ => "unknown".to_string(),
    }
}

fn render_json_schema_array(map: &serde_json::Map<String, JsonValue>) -> String {
    if let Some(items) = map.get("items") {
        let item_type = render_json_schema_to_typescript_inner(items);
        return format!("Array<{item_type}>");
    }

    if let Some(items) = map.get("prefixItems").and_then(JsonValue::as_array) {
        let item_types = items
            .iter()
            .map(render_json_schema_to_typescript_inner)
            .collect::<Vec<_>>();
        if !item_types.is_empty() {
            return format!("[{}]", item_types.join(", "));
        }
    }

    "unknown[]".to_string()
}

fn render_json_schema_object(map: &serde_json::Map<String, JsonValue>) -> String {
    let required = map
        .get("required")
        .and_then(JsonValue::as_array)
        .map(|items| {
            items
                .iter()
                .filter_map(JsonValue::as_str)
                .collect::<Vec<_>>()
        })
        .unwrap_or_default();
    let properties = map
        .get("properties")
        .and_then(JsonValue::as_object)
        .cloned()
        .unwrap_or_default();

    let mut sorted_properties = properties.iter().collect::<Vec<_>>();
    sorted_properties.sort_unstable_by(|(name_a, _), (name_b, _)| name_a.cmp(name_b));
    let mut lines = sorted_properties
        .into_iter()
        .map(|(name, value)| {
            let optional = if required.iter().any(|required_name| required_name == name) {
                ""
            } else {
                "?"
            };
            let property_name = render_json_schema_property_name(name);
            let property_type = render_json_schema_to_typescript_inner(value);
            format!("{property_name}{optional}: {property_type};")
        })
        .collect::<Vec<_>>();

    if let Some(additional_properties) = map.get("additionalProperties") {
        let property_type = match additional_properties {
            JsonValue::Bool(true) => Some("unknown".to_string()),
            JsonValue::Bool(false) => None,
            value => Some(render_json_schema_to_typescript_inner(value)),
        };

        if let Some(property_type) = property_type {
            lines.push(format!("[key: string]: {property_type};"));
        }
    } else if properties.is_empty() {
        lines.push("[key: string]: unknown;".to_string());
    }

    if lines.is_empty() {
        return "{}".to_string();
    }

    format!("{{ {} }}", lines.join(" "))
}

fn render_json_schema_property_name(name: &str) -> String {
    if normalize_code_mode_identifier(name) == name {
        name.to_string()
    } else {
        serde_json::to_string(name).unwrap_or_else(|_| format!("\"{}\"", name.replace('"', "\\\"")))
    }
}

fn render_json_schema_literal(value: &JsonValue) -> String {
    serde_json::to_string(value).unwrap_or_else(|_| "unknown".to_string())
}

#[cfg(test)]
mod tests {
    use super::CodeModeToolKind;
    use super::ParsedExecSource;
    use super::ToolDefinition;
    use super::augment_tool_definition;
    use super::build_exec_tool_description;
    use super::normalize_code_mode_identifier;
    use super::parse_exec_source;
    use pretty_assertions::assert_eq;
    use serde_json::json;

    #[test]
    fn parse_exec_source_without_pragma() {
        assert_eq!(
            parse_exec_source("text('hi')").unwrap(),
            ParsedExecSource {
                code: "text('hi')".to_string(),
                yield_time_ms: None,
                max_output_tokens: None,
            }
        );
    }

    #[test]
    fn parse_exec_source_with_pragma() {
        assert_eq!(
            parse_exec_source("// @exec: {\"yield_time_ms\": 10}\ntext('hi')").unwrap(),
            ParsedExecSource {
                code: "text('hi')".to_string(),
                yield_time_ms: Some(10),
                max_output_tokens: None,
            }
        );
    }

    #[test]
    fn normalize_identifier_rewrites_invalid_characters() {
        assert_eq!(
            "mcp__ologs__get_profile",
            normalize_code_mode_identifier("mcp__ologs__get_profile")
        );
        assert_eq!(
            "hidden_dynamic_tool",
            normalize_code_mode_identifier("hidden-dynamic-tool")
        );
    }

    #[test]
    fn augment_tool_definition_appends_typed_declaration() {
        let definition = ToolDefinition {
            name: "hidden_dynamic_tool".to_string(),
            description: "Test tool".to_string(),
            kind: CodeModeToolKind::Function,
            input_schema: Some(json!({
                "type": "object",
                "properties": { "city": { "type": "string" } },
                "required": ["city"],
                "additionalProperties": false
            })),
            output_schema: Some(json!({
                "type": "object",
                "properties": { "ok": { "type": "boolean" } },
                "required": ["ok"]
            })),
        };

        let description = augment_tool_definition(definition).description;
        assert!(description.contains("declare const tools"));
        assert!(
            description.contains(
                "hidden_dynamic_tool(args: { city: string; }): Promise<{ ok: boolean; }>;"
            )
        );
    }

    #[test]
    fn code_mode_only_description_includes_nested_tools() {
        let description = build_exec_tool_description(
            &[("foo".to_string(), "bar".to_string())],
            /*code_mode_only*/ true,
        );
        assert!(description.contains("### `foo` (`foo`)"));
    }
}