hopper-schema 0.1.0

//! # Client Generation Module
//!
//! Generates typed client SDKs from Hopper schema types.
//!
//! The generator operates on the in-memory schema types (`ProgramManifest`,
//! `LayoutManifest`, `InstructionDescriptor`, etc.) and produces source code
//! via `core::fmt::Display` wrappers.
//!
//! ## Supported Languages
//!
//! - **TypeScript**: Full SDK with accounts, instructions, events, types.
//! - **Kotlin**: Android SDK for Solana Mobile, using `@solana/web3.js` patterns
//!   mapped to `com.solana.mobilewalletadapter` and `org.sol4k`.
//!
//! ## Usage
//!
//! ```text
//! hopper client gen --ts @my-program.manifest.json
//! hopper client gen --kt @my-program.manifest.json
//! ```

use core::fmt;

extern crate alloc;

use crate::{InstructionDescriptor, ProgramManifest};

// ---------------------------------------------------------------------------
// Type Mapping
// ---------------------------------------------------------------------------

/// Map a Hopper canonical type name to a TypeScript type.
fn ts_type(canonical: &str) -> &str {
    match canonical {
        "u8" | "u16" | "u32" | "i8" | "i16" | "i32" => "number",
        "u64" | "u128" | "i64" | "i128" => "bigint",
        "bool" => "boolean",
        "Pubkey" => "PublicKey",
        _ => {
            if canonical.starts_with("[u8;") {
                "Uint8Array"
            } else {
                "Uint8Array" // fallback for unknown types
            }
        }
    }
}

/// PascalCase from snake_case or as-is.
fn write_pascal(f: &mut fmt::Formatter<'_>, name: &str) -> fmt::Result {
    let mut capitalize_next = true;
    for c in name.chars() {
        if c == '_' || c == '-' {
            capitalize_next = true;
        } else if capitalize_next {
            for uc in c.to_uppercase() {
                write!(f, "{}", uc)?;
            }
            capitalize_next = false;
        } else {
            write!(f, "{}", c)?;
        }
    }
    Ok(())
}

/// camelCase from snake_case or as-is.
fn write_camel(f: &mut fmt::Formatter<'_>, name: &str) -> fmt::Result {
    let mut capitalize_next = false;
    let mut first = true;
    for c in name.chars() {
        if c == '_' || c == '-' {
            capitalize_next = true;
        } else if capitalize_next {
            for uc in c.to_uppercase() {
                write!(f, "{}", uc)?;
            }
            capitalize_next = false;
        } else if first {
            for lc in c.to_lowercase() {
                write!(f, "{}", lc)?;
            }
            first = false;
        } else {
            write!(f, "{}", c)?;
        }
    }
    Ok(())
}

// ---------------------------------------------------------------------------
// TypeScript Accounts
// ---------------------------------------------------------------------------

/// Generates `accounts.ts` content from a `ProgramManifest`.
pub struct TsAccounts<'a>(pub &'a ProgramManifest);

impl<'a> fmt::Display for TsAccounts<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let prog = self.0;

        writeln!(f, "// Auto-generated by hopper client gen --ts")?;
        writeln!(f, "// Program: {} v{}", prog.name, prog.version)?;
        writeln!(f, "// DO NOT EDIT")?;
        writeln!(f)?;
        writeln!(f, "import {{ PublicKey }} from \"@solana/web3.js\";")?;
        writeln!(f)?;

        // Header size constant
        writeln!(f, "/** Hopper account header size in bytes. */")?;
        writeln!(f, "export const HEADER_SIZE = 16;")?;
        writeln!(f)?;
        // Offset of the 8-byte LAYOUT_ID fingerprint within the
        // Hopper header. Clients read bytes [4, 12) to assert the
        // account matches the expected layout. See audit ST2 + the
        // "winning architecture" design's client-side ABI guard.
        writeln!(
            f,
            "/** Byte offset of the 8-byte layout fingerprint in a Hopper account header. */"
        )?;
        writeln!(f, "export const LAYOUT_ID_OFFSET = 4;")?;
        writeln!(f, "/** Byte length of the layout fingerprint. */")?;
        writeln!(f, "export const LAYOUT_ID_LENGTH = 8;")?;
        writeln!(f)?;
        // Generic layout-fingerprint verifier. Used by every
        // per-layout `assertXxxLayout(data)` generated below.
        writeln!(f, "/**")?;
        writeln!(
            f,
            " * Raise if `data` is not a Hopper account encoding the expected layout."
        )?;
        writeln!(f, " *")?;
        writeln!(
            f,
            " * Reads the 8-byte LAYOUT_ID fingerprint from the 16-byte Hopper header"
        )?;
        writeln!(
            f,
            " * (bytes 4..12) and compares it against `expectedHex` (16 lowercase hex chars)."
        )?;
        writeln!(
            f,
            " * This is the client-side complement to the runtime check `load::<T>()` runs"
        )?;
        writeln!(
            f,
            " * before handing out a typed Ref. Mismatch means the on-chain program was"
        )?;
        writeln!(
            f,
            " * upgraded with a different ABI than the client was generated against."
        )?;
        writeln!(f, " */")?;
        writeln!(
            f,
            "export function assertLayoutId(data: Uint8Array, expectedHex: string): void {{"
        )?;
        writeln!(f, "  if (data.length < HEADER_SIZE) {{")?;
        writeln!(
            f,
            "    throw new Error(`Hopper account too short: ${{data.length}} < ${{HEADER_SIZE}}`);"
        )?;
        writeln!(f, "  }}")?;
        writeln!(f, "  let actualHex = \"\";")?;
        writeln!(f, "  for (let i = 0; i < LAYOUT_ID_LENGTH; i++) {{")?;
        writeln!(
            f,
            "    actualHex += data[LAYOUT_ID_OFFSET + i].toString(16).padStart(2, \"0\");"
        )?;
        writeln!(f, "  }}")?;
        writeln!(f, "  if (actualHex !== expectedHex.toLowerCase()) {{")?;
        writeln!(f, "    throw new Error(")?;
        writeln!(f, "      `Hopper layout mismatch: account header reports ${{actualHex}}, expected ${{expectedHex}}`,")?;
        writeln!(f, "    );")?;
        writeln!(f, "  }}")?;
        writeln!(f, "}}")?;
        writeln!(f)?;

        for layout in prog.layouts.iter() {
            // Interface
            write!(f, "export interface ")?;
            write_pascal(f, layout.name)?;
            writeln!(f, " {{")?;
            for field in layout.fields.iter() {
                write!(f, "  ")?;
                write_camel(f, field.name)?;
                writeln!(f, ": {};", ts_type(field.canonical_type))?;
            }
            writeln!(f, "}}")?;
            writeln!(f)?;

            // Layout fingerprint constant (hex). Pairs with the
            // runtime's `T::LAYOUT_ID` so the client and the program
            // agree on the ABI byte-for-byte.
            write!(f, "export const ")?;
            write_upper_snake(f, layout.name)?;
            write!(f, "_LAYOUT_ID = \"")?;
            for b in layout.layout_id.iter() {
                write!(f, "{:02x}", b)?;
            }
            writeln!(f, "\";")?;
            writeln!(f)?;

            // Per-layout assertion helper. Thin wrapper over
            // `assertLayoutId` that fills in the expected hex for
            // convenience at call sites.
            write!(f, "export function assert")?;
            write_pascal(f, layout.name)?;
            writeln!(f, "Layout(data: Uint8Array): void {{")?;
            write!(f, "  assertLayoutId(data, ")?;
            write_upper_snake(f, layout.name)?;
            writeln!(f, "_LAYOUT_ID);")?;
            writeln!(f, "}}")?;
            writeln!(f)?;

            // Discriminator constant
            write!(f, "export const ")?;
            write_upper_snake(f, layout.name)?;
            writeln!(f, "_DISC = {};", layout.disc)?;
            writeln!(f)?;

            // Decoder
            write!(f, "export function decode")?;
            write_pascal(f, layout.name)?;
            writeln!(f, "(data: Uint8Array): ")?;
            write!(f, "  ")?;
            write_pascal(f, layout.name)?;
            writeln!(f, " {{")?;
            write!(f, "  assert")?;
            write_pascal(f, layout.name)?;
            writeln!(f, "Layout(data);")?;
            writeln!(f, "  if (data.length < {}) {{", layout.total_size)?;
            writeln!(
                f,
                "    throw new Error(`Data too small for {}: ${{data.length}} < {}`);",
                layout.name, layout.total_size
            )?;
            writeln!(f, "  }}")?;
            writeln!(
                f,
                "  const view = new DataView(data.buffer, data.byteOffset, data.byteLength);"
            )?;

            for field in layout.fields.iter() {
                let offset = field.offset as usize;
                let end = offset + field.size as usize;
                write!(f, "  const ")?;
                write_camel(f, field.name)?;
                write!(f, " = ")?;
                write_decode_expr(f, field.canonical_type, offset, end)?;
                writeln!(f, ";")?;
            }

            writeln!(f, "  return {{")?;
            for field in layout.fields.iter() {
                write!(f, "    ")?;
                write_camel(f, field.name)?;
                writeln!(f, ",")?;
            }
            writeln!(f, "  }};")?;
            writeln!(f, "}}")?;
            writeln!(f)?;
        }

        Ok(())
    }
}

// ---------------------------------------------------------------------------
// TypeScript Instructions
// ---------------------------------------------------------------------------

/// Generates `instructions.ts` content from a `ProgramManifest`.
pub struct TsInstructions<'a>(pub &'a ProgramManifest);

impl<'a> fmt::Display for TsInstructions<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let prog = self.0;

        writeln!(f, "// Auto-generated by hopper client gen --ts")?;
        writeln!(f, "// Program: {} v{}", prog.name, prog.version)?;
        writeln!(f, "// DO NOT EDIT")?;
        writeln!(f)?;
        writeln!(
            f,
            "import {{ PublicKey, TransactionInstruction }} from \"@solana/web3.js\";"
        )?;
        writeln!(f)?;

        for ix in prog.instructions.iter() {
            // Args interface
            if !ix.args.is_empty() {
                write!(f, "export interface ")?;
                write_pascal(f, ix.name)?;
                writeln!(f, "Args {{")?;
                for arg in ix.args.iter() {
                    write!(f, "  ")?;
                    write_camel(f, arg.name)?;
                    writeln!(f, ": {};", ts_type(arg.canonical_type))?;
                }
                writeln!(f, "}}")?;
                writeln!(f)?;
            }

            // Accounts interface
            write!(f, "export interface ")?;
            write_pascal(f, ix.name)?;
            writeln!(f, "Accounts {{")?;
            for acc in ix.accounts.iter() {
                write!(f, "  ")?;
                write_camel(f, acc.name)?;
                writeln!(f, ": PublicKey;")?;
            }
            writeln!(f, "}}")?;
            writeln!(f)?;

            // Builder function
            write!(f, "export function create")?;
            write_pascal(f, ix.name)?;
            writeln!(f, "Instruction(")?;
            if !ix.args.is_empty() {
                write!(f, "  args: ")?;
                write_pascal(f, ix.name)?;
                writeln!(f, "Args,")?;
            }
            write!(f, "  accounts: ")?;
            write_pascal(f, ix.name)?;
            writeln!(f, "Accounts,")?;
            writeln!(f, "  programId: PublicKey,")?;
            writeln!(f, "): TransactionInstruction {{")?;

            // Build instruction data
            let data_size = instruction_data_size(ix);
            writeln!(f, "  const data = new Uint8Array({});", data_size)?;
            writeln!(f, "  const view = new DataView(data.buffer);")?;
            writeln!(f, "  data[0] = {}; // instruction discriminator", ix.tag)?;

            let mut offset = 1usize; // first byte is tag
            for arg in ix.args.iter() {
                write_encode_expr(f, arg.canonical_type, arg.name, offset)?;
                offset += arg.size as usize;
            }

            writeln!(f)?;

            // Build keys array
            writeln!(f, "  const keys = [")?;
            for acc in ix.accounts.iter() {
                write!(f, "    {{ pubkey: accounts.")?;
                write_camel(f, acc.name)?;
                writeln!(
                    f,
                    ", isSigner: {}, isWritable: {} }},",
                    acc.signer, acc.writable
                )?;
            }
            writeln!(f, "  ];")?;
            writeln!(f)?;
            writeln!(
                f,
                "  return new TransactionInstruction({{ keys, programId, data }});"
            )?;
            writeln!(f, "}}")?;
            writeln!(f)?;
        }

        Ok(())
    }
}

// ---------------------------------------------------------------------------
// TypeScript Events
// ---------------------------------------------------------------------------

/// Generates `events.ts` content from a `ProgramManifest`.
pub struct TsEvents<'a>(pub &'a ProgramManifest);

impl<'a> fmt::Display for TsEvents<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let prog = self.0;

        writeln!(f, "// Auto-generated by hopper client gen --ts")?;
        writeln!(f, "// Program: {} v{}", prog.name, prog.version)?;
        writeln!(f, "// DO NOT EDIT")?;
        writeln!(f)?;
        writeln!(f, "import {{ PublicKey }} from \"@solana/web3.js\";")?;
        writeln!(f)?;

        if prog.events.is_empty() {
            writeln!(f, "// No events defined for this program.")?;
            return Ok(());
        }

        for event in prog.events.iter() {
            // Interface
            write!(f, "export interface ")?;
            write_pascal(f, event.name)?;
            writeln!(f, "Event {{")?;
            for field in event.fields.iter() {
                write!(f, "  ")?;
                write_camel(f, field.name)?;
                writeln!(f, ": {};", ts_type(field.canonical_type))?;
            }
            writeln!(f, "}}")?;
            writeln!(f)?;

            // Discriminator constant
            write!(f, "export const ")?;
            write_upper_snake(f, event.name)?;
            writeln!(f, "_EVENT_DISC = {};", event.tag)?;
            writeln!(f)?;

            // Decoder
            write!(f, "export function decode")?;
            write_pascal(f, event.name)?;
            writeln!(f, "Event(data: Uint8Array): ")?;
            write!(f, "  ")?;
            write_pascal(f, event.name)?;
            writeln!(f, "Event {{")?;
            writeln!(
                f,
                "  const view = new DataView(data.buffer, data.byteOffset, data.byteLength);"
            )?;

            for field in event.fields.iter() {
                let offset = field.offset as usize;
                let end = offset + field.size as usize;
                write!(f, "  const ")?;
                write_camel(f, field.name)?;
                write!(f, " = ")?;
                write_decode_expr(f, field.canonical_type, offset, end)?;
                writeln!(f, ";")?;
            }

            writeln!(f, "  return {{")?;
            for field in event.fields.iter() {
                write!(f, "    ")?;
                write_camel(f, field.name)?;
                writeln!(f, ",")?;
            }
            writeln!(f, "  }};")?;
            writeln!(f, "}}")?;
            writeln!(f)?;
        }

        Ok(())
    }
}

// ---------------------------------------------------------------------------
// TypeScript Types
// ---------------------------------------------------------------------------

/// Generates `types.ts` content (shared type aliases).
pub struct TsTypes<'a>(pub &'a ProgramManifest);

impl<'a> fmt::Display for TsTypes<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let prog = self.0;

        writeln!(f, "// Auto-generated by hopper client gen --ts")?;
        writeln!(f, "// Program: {} v{}", prog.name, prog.version)?;
        writeln!(f, "// DO NOT EDIT")?;
        writeln!(f)?;
        writeln!(f, "import {{ PublicKey }} from \"@solana/web3.js\";")?;
        writeln!(f)?;
        writeln!(f, "/** Hopper account header (16 bytes). */")?;
        writeln!(f, "export interface HopperHeader {{")?;
        writeln!(f, "  disc: number;")?;
        writeln!(f, "  version: number;")?;
        writeln!(f, "  flags: number;")?;
        writeln!(f, "  layoutId: Uint8Array;")?;
        writeln!(f, "  reserved: Uint8Array;")?;
        writeln!(f, "}}")?;
        writeln!(f)?;
        writeln!(f, "const HEADER_SIZE = 16;")?;
        writeln!(f, "const LAYOUT_ID_OFFSET = 4;")?;
        writeln!(f, "const LAYOUT_ID_LENGTH = 8;")?;
        writeln!(f)?;
        writeln!(f, "/** Decode the Hopper 16-byte account header. */")?;
        writeln!(
            f,
            "export function decodeHeader(data: Uint8Array): HopperHeader {{"
        )?;
        writeln!(f, "  if (data.length < HEADER_SIZE) {{")?;
        writeln!(
            f,
            "    throw new Error(`Hopper account too short: ${{data.length}} < ${{HEADER_SIZE}}`);"
        )?;
        writeln!(f, "  }}")?;
        writeln!(
            f,
            "  const view = new DataView(data.buffer, data.byteOffset, data.byteLength);"
        )?;
        writeln!(f, "  return {{")?;
        writeln!(f, "    disc: data[0],")?;
        writeln!(f, "    version: data[1],")?;
        writeln!(f, "    flags: view.getUint16(2, true),")?;
        writeln!(
            f,
            "    layoutId: data.slice(LAYOUT_ID_OFFSET, LAYOUT_ID_OFFSET + LAYOUT_ID_LENGTH),"
        )?;
        writeln!(f, "    reserved: data.slice(12, 16),")?;
        writeln!(f, "  }};")?;
        writeln!(f, "}}")?;
        writeln!(f)?;
        writeln!(
            f,
            "/** All account discriminators for {} v{}. */",
            prog.name, prog.version
        )?;
        writeln!(f, "export const Discriminators = {{")?;
        for layout in prog.layouts.iter() {
            write!(f, "  ")?;
            write_pascal(f, layout.name)?;
            writeln!(f, ": {},", layout.disc)?;
        }
        writeln!(f, "}} as const;")?;

        Ok(())
    }
}

// ---------------------------------------------------------------------------
// TypeScript Index
// ---------------------------------------------------------------------------

/// Generates `index.ts` content (re-exports).
pub struct TsIndex<'a>(pub &'a ProgramManifest);

impl<'a> fmt::Display for TsIndex<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let prog = self.0;

        writeln!(f, "// Auto-generated by hopper client gen --ts")?;
        writeln!(f, "// Program: {} v{}", prog.name, prog.version)?;
        writeln!(f, "// DO NOT EDIT")?;
        writeln!(f)?;
        writeln!(f, "export * from \"./types\";")?;
        writeln!(f, "export * from \"./accounts\";")?;
        writeln!(f, "export * from \"./instructions\";")?;
        writeln!(f, "export * from \"./events\";")?;

        Ok(())
    }
}

// ---------------------------------------------------------------------------
// Full Client Generator
// ---------------------------------------------------------------------------

/// Generates all TypeScript client files for a program and writes them
/// using newline separators with file markers.
///
/// Output format:
/// ```text
/// === accounts.ts ===
/// <contents>
/// === instructions.ts ===
/// <contents>
/// === events.ts ===
/// <contents>
/// === types.ts ===
/// <contents>
/// === index.ts ===
/// <contents>
/// ```
pub struct TsClientGen<'a>(pub &'a ProgramManifest);

impl<'a> fmt::Display for TsClientGen<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let prog = self.0;

        writeln!(f, "=== types.ts ===")?;
        write!(f, "{}", TsTypes(prog))?;
        writeln!(f)?;

        writeln!(f, "=== accounts.ts ===")?;
        write!(f, "{}", TsAccounts(prog))?;
        writeln!(f)?;

        writeln!(f, "=== instructions.ts ===")?;
        write!(f, "{}", TsInstructions(prog))?;
        writeln!(f)?;

        writeln!(f, "=== events.ts ===")?;
        write!(f, "{}", TsEvents(prog))?;
        writeln!(f)?;

        writeln!(f, "=== index.ts ===")?;
        write!(f, "{}", TsIndex(prog))?;

        Ok(())
    }
}

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

fn write_upper_snake(f: &mut fmt::Formatter<'_>, name: &str) -> fmt::Result {
    for c in name.chars() {
        if c == '-' || c == ' ' {
            write!(f, "_")?;
        } else {
            for uc in c.to_uppercase() {
                write!(f, "{}", uc)?;
            }
        }
    }
    Ok(())
}

fn write_decode_expr(
    f: &mut fmt::Formatter<'_>,
    canonical: &str,
    offset: usize,
    end: usize,
) -> fmt::Result {
    match canonical {
        "u8" => write!(f, "data[{}]", offset),
        "i8" => write!(f, "view.getInt8({})", offset),
        "u16" => write!(f, "view.getUint16({}, true)", offset),
        "i16" => write!(f, "view.getInt16({}, true)", offset),
        "u32" => write!(f, "view.getUint32({}, true)", offset),
        "i32" => write!(f, "view.getInt32({}, true)", offset),
        "u64" => write!(f, "view.getBigUint64({}, true)", offset),
        "i64" => write!(f, "view.getBigInt64({}, true)", offset),
        "u128" => {
            write!(
                f,
                "view.getBigUint64({}, true) | (view.getBigUint64({}, true) << 64n)",
                offset,
                offset + 8
            )
        }
        "i128" => {
            write!(
                f,
                "view.getBigInt64({}, true) | (view.getBigUint64({}, true) << 64n)",
                offset + 8,
                offset
            )
        }
        "bool" => write!(f, "data[{}] !== 0", offset),
        "Pubkey" => write!(f, "new PublicKey(data.slice({}, {}))", offset, end),
        _ => write!(f, "data.slice({}, {})", offset, end),
    }
}

fn write_encode_expr(
    f: &mut fmt::Formatter<'_>,
    canonical: &str,
    name: &str,
    offset: usize,
) -> fmt::Result {
    match canonical {
        "u8" => {
            write!(f, "  data[{}] = args.", offset)?;
            write_camel(f, name)?;
            writeln!(f, ";")
        }
        "i8" => {
            write!(f, "  view.setInt8({}, args.", offset)?;
            write_camel(f, name)?;
            writeln!(f, ");")
        }
        "u16" => {
            write!(f, "  view.setUint16({}, args.", offset)?;
            write_camel(f, name)?;
            writeln!(f, ", true);")
        }
        "i16" => {
            write!(f, "  view.setInt16({}, args.", offset)?;
            write_camel(f, name)?;
            writeln!(f, ", true);")
        }
        "u32" => {
            write!(f, "  view.setUint32({}, args.", offset)?;
            write_camel(f, name)?;
            writeln!(f, ", true);")
        }
        "i32" => {
            write!(f, "  view.setInt32({}, args.", offset)?;
            write_camel(f, name)?;
            writeln!(f, ", true);")
        }
        "u64" => {
            write!(f, "  view.setBigUint64({}, args.", offset)?;
            write_camel(f, name)?;
            writeln!(f, ", true);")
        }
        "i64" => {
            write!(f, "  view.setBigInt64({}, args.", offset)?;
            write_camel(f, name)?;
            writeln!(f, ", true);")
        }
        "u128" => {
            write!(f, "  view.setBigUint64({}, args.", offset)?;
            write_camel(f, name)?;
            writeln!(f, " & 0xFFFFFFFFFFFFFFFFn, true);")?;
            write!(f, "  view.setBigUint64({}, args.", offset + 8)?;
            write_camel(f, name)?;
            writeln!(f, " >> 64n, true);")
        }
        "bool" => {
            write!(f, "  data[{}] = args.", offset)?;
            write_camel(f, name)?;
            writeln!(f, " ? 1 : 0;")
        }
        "Pubkey" => {
            write!(f, "  data.set(args.")?;
            write_camel(f, name)?;
            writeln!(f, ".toBytes(), {});", offset)
        }
        _ => {
            write!(f, "  data.set(args.")?;
            write_camel(f, name)?;
            writeln!(f, ", {});", offset)
        }
    }
}

fn instruction_data_size(ix: &InstructionDescriptor) -> usize {
    let mut size = 1usize; // discriminator byte
    for arg in ix.args.iter() {
        size += arg.size as usize;
    }
    size
}

// ---------------------------------------------------------------------------
// Kotlin Type Mapping
// ---------------------------------------------------------------------------

/// Map a Hopper canonical type name to a Kotlin type.
fn kt_type(canonical: &str) -> &str {
    match canonical {
        "u8" => "UByte",
        "i8" => "Byte",
        "u16" => "UShort",
        "i16" => "Short",
        "u32" => "UInt",
        "i32" => "Int",
        "u64" => "ULong",
        "i64" => "Long",
        "u128" | "i128" => "ByteArray",
        "bool" => "Boolean",
        "Pubkey" => "PublicKey",
        _ => {
            if canonical.starts_with("[u8;") {
                "ByteArray"
            } else {
                "ByteArray"
            }
        }
    }
}

/// Write PascalCase (used for Kotlin classes/interfaces).
fn write_kt_pascal(f: &mut fmt::Formatter<'_>, name: &str) -> fmt::Result {
    write_pascal(f, name)
}

/// Write camelCase (used for Kotlin properties/functions).
fn write_kt_camel(f: &mut fmt::Formatter<'_>, name: &str) -> fmt::Result {
    write_camel(f, name)
}

/// Write SCREAMING_SNAKE_CASE for constants.
fn write_kt_const(f: &mut fmt::Formatter<'_>, name: &str) -> fmt::Result {
    write_upper_snake(f, name)
}

fn write_kt_decode_expr(
    f: &mut fmt::Formatter<'_>,
    canonical: &str,
    offset: usize,
    end: usize,
) -> fmt::Result {
    match canonical {
        "u8" => write!(f, "data[{}].toUByte()", offset),
        "i8" => write!(f, "data[{}]", offset),
        "u16" => write!(
            f,
            "ByteBuffer.wrap(data, {}, 2).order(ByteOrder.LITTLE_ENDIAN).short.toUShort()",
            offset
        ),
        "i16" => write!(
            f,
            "ByteBuffer.wrap(data, {}, 2).order(ByteOrder.LITTLE_ENDIAN).short",
            offset
        ),
        "u32" => write!(
            f,
            "ByteBuffer.wrap(data, {}, 4).order(ByteOrder.LITTLE_ENDIAN).int.toUInt()",
            offset
        ),
        "i32" => write!(
            f,
            "ByteBuffer.wrap(data, {}, 4).order(ByteOrder.LITTLE_ENDIAN).int",
            offset
        ),
        "u64" => write!(
            f,
            "ByteBuffer.wrap(data, {}, 8).order(ByteOrder.LITTLE_ENDIAN).long.toULong()",
            offset
        ),
        "i64" => write!(
            f,
            "ByteBuffer.wrap(data, {}, 8).order(ByteOrder.LITTLE_ENDIAN).long",
            offset
        ),
        "u128" | "i128" => write!(f, "data.copyOfRange({}, {})", offset, end),
        "bool" => write!(f, "data[{}] != 0.toByte()", offset),
        "Pubkey" => write!(f, "PublicKey(data.copyOfRange({}, {}))", offset, end),
        _ => write!(f, "data.copyOfRange({}, {})", offset, end),
    }
}

fn write_kt_encode_expr(
    f: &mut fmt::Formatter<'_>,
    canonical: &str,
    name: &str,
    offset: usize,
) -> fmt::Result {
    match canonical {
        "u8" => {
            write!(f, "    data[{}] = args.", offset)?;
            write_kt_camel(f, name)?;
            writeln!(f, ".toByte()")
        }
        "i8" => {
            write!(f, "    data[{}] = args.", offset)?;
            write_kt_camel(f, name)?;
            writeln!(f, "")
        }
        "u16" => {
            write!(
                f,
                "    ByteBuffer.wrap(data, {}, 2).order(ByteOrder.LITTLE_ENDIAN).putShort(args.",
                offset
            )?;
            write_kt_camel(f, name)?;
            writeln!(f, ".toShort())")
        }
        "i16" => {
            write!(
                f,
                "    ByteBuffer.wrap(data, {}, 2).order(ByteOrder.LITTLE_ENDIAN).putShort(args.",
                offset
            )?;
            write_kt_camel(f, name)?;
            writeln!(f, ")")
        }
        "u32" => {
            write!(
                f,
                "    ByteBuffer.wrap(data, {}, 4).order(ByteOrder.LITTLE_ENDIAN).putInt(args.",
                offset
            )?;
            write_kt_camel(f, name)?;
            writeln!(f, ".toInt())")
        }
        "i32" => {
            write!(
                f,
                "    ByteBuffer.wrap(data, {}, 4).order(ByteOrder.LITTLE_ENDIAN).putInt(args.",
                offset
            )?;
            write_kt_camel(f, name)?;
            writeln!(f, ")")
        }
        "u64" => {
            write!(
                f,
                "    ByteBuffer.wrap(data, {}, 8).order(ByteOrder.LITTLE_ENDIAN).putLong(args.",
                offset
            )?;
            write_kt_camel(f, name)?;
            writeln!(f, ".toLong())")
        }
        "i64" => {
            write!(
                f,
                "    ByteBuffer.wrap(data, {}, 8).order(ByteOrder.LITTLE_ENDIAN).putLong(args.",
                offset
            )?;
            write_kt_camel(f, name)?;
            writeln!(f, ")")
        }
        "bool" => {
            write!(f, "    data[{}] = if (args.", offset)?;
            write_kt_camel(f, name)?;
            writeln!(f, ") 1.toByte() else 0.toByte()")
        }
        "Pubkey" => {
            write!(f, "    args.")?;
            write_kt_camel(f, name)?;
            writeln!(f, ".toByteArray().copyInto(data, {})", offset)
        }
        _ => {
            write!(f, "    args.")?;
            write_kt_camel(f, name)?;
            writeln!(f, ".copyInto(data, {})", offset)
        }
    }
}

// ---------------------------------------------------------------------------
// Kotlin Accounts
// ---------------------------------------------------------------------------

/// Generates Kotlin data classes and decoders for account layouts.
pub struct KtAccounts<'a>(pub &'a ProgramManifest);

impl<'a> fmt::Display for KtAccounts<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let prog = self.0;

        writeln!(f, "// Auto-generated by hopper client gen --kt")?;
        writeln!(f, "// Program: {} v{}", prog.name, prog.version)?;
        writeln!(f, "// DO NOT EDIT")?;
        writeln!(f)?;
        writeln!(
            f,
            "package hopper.generated.{}",
            prog.name.replace('-', "_")
        )?;
        writeln!(f)?;
        writeln!(f, "import org.sol4k.PublicKey")?;
        writeln!(f, "import java.nio.ByteBuffer")?;
        writeln!(f, "import java.nio.ByteOrder")?;
        writeln!(f)?;

        // Hopper header layout constants. The 16-byte header carries the
        // 8-byte LAYOUT_ID at bytes [4, 12). Clients compare this against
        // the compiled-in per-layout constant before decoding, which is
        // the client-side complement to the runtime's `load::<T>()`
        // fingerprint check.
        writeln!(f, "/** Hopper account header size in bytes. */")?;
        writeln!(f, "const val HEADER_SIZE: Int = 16")?;
        writeln!(
            f,
            "/** Byte offset of the 8-byte layout fingerprint in a Hopper header. */"
        )?;
        writeln!(f, "const val LAYOUT_ID_OFFSET: Int = 4")?;
        writeln!(f, "/** Byte length of the layout fingerprint. */")?;
        writeln!(f, "const val LAYOUT_ID_LENGTH: Int = 8")?;
        writeln!(f)?;

        writeln!(
            f,
            "class LayoutMismatchException(expected: String, actual: String) :"
        )?;
        writeln!(f, "    RuntimeException(\"Hopper layout mismatch: account header reports $actual, expected $expected\")")?;
        writeln!(f)?;

        writeln!(f, "/**")?;
        writeln!(
            f,
            " * Raise if `data` is not a Hopper account encoding the expected layout."
        )?;
        writeln!(f, " *")?;
        writeln!(
            f,
            " * Reads the 8-byte LAYOUT_ID fingerprint from the 16-byte Hopper header"
        )?;
        writeln!(
            f,
            " * (bytes 4..12) and compares it against `expectedHex` (16 lowercase hex chars)."
        )?;
        writeln!(
            f,
            " * Mismatch means the on-chain program was upgraded with a different ABI"
        )?;
        writeln!(f, " * than the client was generated against.")?;
        writeln!(f, " */")?;
        writeln!(
            f,
            "fun assertLayoutId(data: ByteArray, expectedHex: String) {{"
        )?;
        writeln!(f, "    if (data.size < HEADER_SIZE) {{")?;
        writeln!(f, "        throw RuntimeException(\"Hopper account too short: ${{data.size}} < $HEADER_SIZE\")")?;
        writeln!(f, "    }}")?;
        writeln!(f, "    val sb = StringBuilder(LAYOUT_ID_LENGTH * 2)")?;
        writeln!(f, "    for (i in 0 until LAYOUT_ID_LENGTH) {{")?;
        writeln!(
            f,
            "        val byte = data[LAYOUT_ID_OFFSET + i].toInt() and 0xFF"
        )?;
        writeln!(f, "        sb.append(String.format(\"%02x\", byte))")?;
        writeln!(f, "    }}")?;
        writeln!(f, "    val actualHex = sb.toString()")?;
        writeln!(f, "    if (actualHex != expectedHex.lowercase()) {{")?;
        writeln!(
            f,
            "        throw LayoutMismatchException(expectedHex, actualHex)"
        )?;
        writeln!(f, "    }}")?;
        writeln!(f, "}}")?;
        writeln!(f)?;

        for layout in prog.layouts.iter() {
            // Data class
            write!(f, "data class ")?;
            write_kt_pascal(f, layout.name)?;
            writeln!(f, "(")?;
            for (i, field) in layout.fields.iter().enumerate() {
                write!(f, "    val ")?;
                write_kt_camel(f, field.name)?;
                write!(f, ": {}", kt_type(field.canonical_type))?;
                if i + 1 < layout.fields.len() {
                    writeln!(f, ",")?;
                } else {
                    writeln!(f)?;
                }
            }
            writeln!(f, ")")?;
            writeln!(f)?;

            // Layout fingerprint constant (hex). Pairs with the
            // runtime's `T::LAYOUT_ID` so the client and the program
            // agree on the ABI byte-for-byte.
            write!(f, "const val ")?;
            write_kt_const(f, layout.name)?;
            write!(f, "_LAYOUT_ID: String = \"")?;
            for b in layout.layout_id.iter() {
                write!(f, "{:02x}", b)?;
            }
            writeln!(f, "\"")?;
            writeln!(f)?;

            // Per-layout assertion helper. Thin wrapper over
            // `assertLayoutId` that fills in the expected hex.
            write!(f, "fun assert")?;
            write_kt_pascal(f, layout.name)?;
            writeln!(f, "Layout(data: ByteArray) {{")?;
            write!(f, "    assertLayoutId(data, ")?;
            write_kt_const(f, layout.name)?;
            writeln!(f, "_LAYOUT_ID)")?;
            writeln!(f, "}}")?;
            writeln!(f)?;

            // Discriminator constant
            write!(f, "const val ")?;
            write_kt_const(f, layout.name)?;
            writeln!(f, "_DISC: Byte = {}", layout.disc)?;
            writeln!(f)?;

            // Decoder
            write!(f, "fun decode")?;
            write_kt_pascal(f, layout.name)?;
            write!(f, "(data: ByteArray): ")?;
            write_kt_pascal(f, layout.name)?;
            writeln!(f, " {{")?;
            write!(f, "    assert")?;
            write_kt_pascal(f, layout.name)?;
            writeln!(f, "Layout(data)")?;
            writeln!(
                f,
                "    require(data.size >= {}) {{ \"Data too small for {}\" }}",
                layout.total_size, layout.name
            )?;

            for field in layout.fields.iter() {
                let offset = field.offset as usize;
                let end = offset + field.size as usize;
                write!(f, "    val ")?;
                write_kt_camel(f, field.name)?;
                write!(f, " = ")?;
                write_kt_decode_expr(f, field.canonical_type, offset, end)?;
                writeln!(f)?;
            }

            write!(f, "    return ")?;
            write_kt_pascal(f, layout.name)?;
            writeln!(f, "(")?;
            for (i, field) in layout.fields.iter().enumerate() {
                write!(f, "        ")?;
                write_kt_camel(f, field.name)?;
                write!(f, " = ")?;
                write_kt_camel(f, field.name)?;
                if i + 1 < layout.fields.len() {
                    writeln!(f, ",")?;
                } else {
                    writeln!(f)?;
                }
            }
            writeln!(f, "    )")?;
            writeln!(f, "}}")?;
            writeln!(f)?;
        }

        Ok(())
    }
}

// ---------------------------------------------------------------------------
// Kotlin Instructions
// ---------------------------------------------------------------------------

/// Generates Kotlin instruction builders from a `ProgramManifest`.
pub struct KtInstructions<'a>(pub &'a ProgramManifest);

impl<'a> fmt::Display for KtInstructions<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let prog = self.0;

        writeln!(f, "// Auto-generated by hopper client gen --kt")?;
        writeln!(f, "// Program: {} v{}", prog.name, prog.version)?;
        writeln!(f, "// DO NOT EDIT")?;
        writeln!(f)?;
        writeln!(
            f,
            "package hopper.generated.{}",
            prog.name.replace('-', "_")
        )?;
        writeln!(f)?;
        writeln!(f, "import org.sol4k.PublicKey")?;
        writeln!(f, "import org.sol4k.instruction.AccountMeta")?;
        writeln!(f, "import org.sol4k.instruction.Instruction")?;
        writeln!(f, "import java.nio.ByteBuffer")?;
        writeln!(f, "import java.nio.ByteOrder")?;
        writeln!(f)?;

        for ix in prog.instructions.iter() {
            // Args data class
            if !ix.args.is_empty() {
                write!(f, "data class ")?;
                write_kt_pascal(f, ix.name)?;
                writeln!(f, "Args(")?;
                for (i, arg) in ix.args.iter().enumerate() {
                    write!(f, "    val ")?;
                    write_kt_camel(f, arg.name)?;
                    write!(f, ": {}", kt_type(arg.canonical_type))?;
                    if i + 1 < ix.args.len() {
                        writeln!(f, ",")?;
                    } else {
                        writeln!(f)?;
                    }
                }
                writeln!(f, ")")?;
                writeln!(f)?;
            }

            // Accounts data class
            write!(f, "data class ")?;
            write_kt_pascal(f, ix.name)?;
            writeln!(f, "Accounts(")?;
            for (i, acc) in ix.accounts.iter().enumerate() {
                write!(f, "    val ")?;
                write_kt_camel(f, acc.name)?;
                write!(f, ": PublicKey")?;
                if i + 1 < ix.accounts.len() {
                    writeln!(f, ",")?;
                } else {
                    writeln!(f)?;
                }
            }
            writeln!(f, ")")?;
            writeln!(f)?;

            // Builder function
            write!(f, "fun create")?;
            write_kt_pascal(f, ix.name)?;
            writeln!(f, "Instruction(")?;
            if !ix.args.is_empty() {
                write!(f, "    args: ")?;
                write_kt_pascal(f, ix.name)?;
                writeln!(f, "Args,")?;
            }
            write!(f, "    accounts: ")?;
            write_kt_pascal(f, ix.name)?;
            writeln!(f, "Accounts,")?;
            writeln!(f, "    programId: PublicKey,")?;
            writeln!(f, "): Instruction {{")?;

            let data_size = instruction_data_size(ix);
            writeln!(f, "    val data = ByteArray({})", data_size)?;
            writeln!(
                f,
                "    data[0] = {}.toByte() // instruction discriminator",
                ix.tag
            )?;

            let mut offset = 1usize;
            for arg in ix.args.iter() {
                write_kt_encode_expr(f, arg.canonical_type, arg.name, offset)?;
                offset += arg.size as usize;
            }

            writeln!(f)?;
            writeln!(f, "    val keys = listOf(")?;
            for acc in ix.accounts.iter() {
                write!(f, "        AccountMeta(accounts.")?;
                write_kt_camel(f, acc.name)?;
                writeln!(
                    f,
                    ", isSigner = {}, isWritable = {}),",
                    acc.signer, acc.writable
                )?;
            }
            writeln!(f, "    )")?;
            writeln!(f)?;
            writeln!(f, "    return Instruction(programId, keys, data)")?;
            writeln!(f, "}}")?;
            writeln!(f)?;
        }

        Ok(())
    }
}

// ---------------------------------------------------------------------------
// Kotlin Events
// ---------------------------------------------------------------------------

/// Generates Kotlin event data classes and decoders.
pub struct KtEvents<'a>(pub &'a ProgramManifest);

impl<'a> fmt::Display for KtEvents<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let prog = self.0;

        writeln!(f, "// Auto-generated by hopper client gen --kt")?;
        writeln!(f, "// Program: {} v{}", prog.name, prog.version)?;
        writeln!(f, "// DO NOT EDIT")?;
        writeln!(f)?;
        writeln!(
            f,
            "package hopper.generated.{}",
            prog.name.replace('-', "_")
        )?;
        writeln!(f)?;
        writeln!(f, "import org.sol4k.PublicKey")?;
        writeln!(f, "import java.nio.ByteBuffer")?;
        writeln!(f, "import java.nio.ByteOrder")?;
        writeln!(f)?;

        if prog.events.is_empty() {
            writeln!(f, "// No events defined for this program.")?;
            return Ok(());
        }

        for event in prog.events.iter() {
            write!(f, "data class ")?;
            write_kt_pascal(f, event.name)?;
            writeln!(f, "Event(")?;
            for (i, field) in event.fields.iter().enumerate() {
                write!(f, "    val ")?;
                write_kt_camel(f, field.name)?;
                write!(f, ": {}", kt_type(field.canonical_type))?;
                if i + 1 < event.fields.len() {
                    writeln!(f, ",")?;
                } else {
                    writeln!(f)?;
                }
            }
            writeln!(f, ")")?;
            writeln!(f)?;

            write!(f, "const val ")?;
            write_kt_const(f, event.name)?;
            writeln!(f, "_EVENT_DISC: Byte = {}", event.tag)?;
            writeln!(f)?;

            write!(f, "fun decode")?;
            write_kt_pascal(f, event.name)?;
            write!(f, "Event(data: ByteArray): ")?;
            write_kt_pascal(f, event.name)?;
            writeln!(f, "Event {{")?;

            for field in event.fields.iter() {
                let offset = field.offset as usize;
                let end = offset + field.size as usize;
                write!(f, "    val ")?;
                write_kt_camel(f, field.name)?;
                write!(f, " = ")?;
                write_kt_decode_expr(f, field.canonical_type, offset, end)?;
                writeln!(f)?;
            }

            write!(f, "    return ")?;
            write_kt_pascal(f, event.name)?;
            writeln!(f, "Event(")?;
            for (i, field) in event.fields.iter().enumerate() {
                write!(f, "        ")?;
                write_kt_camel(f, field.name)?;
                write!(f, " = ")?;
                write_kt_camel(f, field.name)?;
                if i + 1 < event.fields.len() {
                    writeln!(f, ",")?;
                } else {
                    writeln!(f)?;
                }
            }
            writeln!(f, "    )")?;
            writeln!(f, "}}")?;
            writeln!(f)?;
        }

        Ok(())
    }
}

// ---------------------------------------------------------------------------
// Kotlin Types
// ---------------------------------------------------------------------------

/// Generates Kotlin header type and discriminator constants.
pub struct KtTypes<'a>(pub &'a ProgramManifest);

impl<'a> fmt::Display for KtTypes<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let prog = self.0;

        writeln!(f, "// Auto-generated by hopper client gen --kt")?;
        writeln!(f, "// Program: {} v{}", prog.name, prog.version)?;
        writeln!(f, "// DO NOT EDIT")?;
        writeln!(f)?;
        writeln!(
            f,
            "package hopper.generated.{}",
            prog.name.replace('-', "_")
        )?;
        writeln!(f)?;
        writeln!(f, "import java.nio.ByteBuffer")?;
        writeln!(f, "import java.nio.ByteOrder")?;
        writeln!(f)?;
        writeln!(f, "/** Hopper account header (16 bytes). */")?;
        writeln!(f, "data class HopperHeader(")?;
        writeln!(f, "    val disc: UByte,")?;
        writeln!(f, "    val version: UByte,")?;
        writeln!(f, "    val flags: UShort,")?;
        writeln!(f, "    val layoutId: ByteArray,")?;
        writeln!(f, "    val reserved: ByteArray")?;
        writeln!(f, ")")?;
        writeln!(f)?;
        writeln!(f, "private const val TYPES_HEADER_SIZE: Int = 16")?;
        writeln!(f, "private const val TYPES_LAYOUT_ID_OFFSET: Int = 4")?;
        writeln!(f, "private const val TYPES_LAYOUT_ID_LENGTH: Int = 8")?;
        writeln!(f)?;
        writeln!(f, "/** Decode the Hopper 16-byte account header. */")?;
        writeln!(f, "fun decodeHeader(data: ByteArray): HopperHeader {{")?;
        writeln!(
            f,
            "    require(data.size >= TYPES_HEADER_SIZE) {{ \"Data too small for header\" }}"
        )?;
        writeln!(f, "    return HopperHeader(")?;
        writeln!(f, "        disc = data[0].toUByte(),")?;
        writeln!(f, "        version = data[1].toUByte(),")?;
        writeln!(
            f,
            "        flags = ByteBuffer.wrap(data, 2, 2).order(ByteOrder.LITTLE_ENDIAN).short.toUShort(),"
        )?;
        writeln!(
            f,
            "        layoutId = data.copyOfRange(TYPES_LAYOUT_ID_OFFSET, TYPES_LAYOUT_ID_OFFSET + TYPES_LAYOUT_ID_LENGTH),"
        )?;
        writeln!(f, "        reserved = data.copyOfRange(12, 16)")?;
        writeln!(f, "    )")?;
        writeln!(f, "}}")?;
        writeln!(f)?;
        writeln!(
            f,
            "/** All account discriminators for {} v{}. */",
            prog.name, prog.version
        )?;
        writeln!(f, "object Discriminators {{")?;
        for layout in prog.layouts.iter() {
            write!(f, "    const val ")?;
            write_kt_const(f, layout.name)?;
            writeln!(f, ": Byte = {}", layout.disc)?;
        }
        writeln!(f, "}}")?;

        Ok(())
    }
}

// ---------------------------------------------------------------------------
// Full Kotlin Client Generator
// ---------------------------------------------------------------------------

/// Generates all Kotlin client files for a program.
///
/// Output format uses file markers like the TypeScript generator:
/// ```text
/// === Types.kt ===
/// <contents>
/// === Accounts.kt ===
/// <contents>
/// === Instructions.kt ===
/// <contents>
/// === Events.kt ===
/// <contents>
/// ```
pub struct KtClientGen<'a>(pub &'a ProgramManifest);

impl<'a> fmt::Display for KtClientGen<'a> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let prog = self.0;

        writeln!(f, "=== Types.kt ===")?;
        write!(f, "{}", KtTypes(prog))?;
        writeln!(f)?;

        writeln!(f, "=== Accounts.kt ===")?;
        write!(f, "{}", KtAccounts(prog))?;
        writeln!(f)?;

        writeln!(f, "=== Instructions.kt ===")?;
        write!(f, "{}", KtInstructions(prog))?;
        writeln!(f)?;

        writeln!(f, "=== Events.kt ===")?;
        write!(f, "{}", KtEvents(prog))?;

        Ok(())
    }
}

// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------

#[cfg(test)]
mod tests {
    extern crate alloc;
    use super::*;
    use crate::{
        AccountEntry, ArgDescriptor, EventDescriptor, FieldDescriptor, FieldIntent, LayoutManifest,
    };
    use alloc::string::ToString;

    fn test_manifest() -> ProgramManifest {
        static FIELDS: &[FieldDescriptor] = &[
            FieldDescriptor {
                name: "authority",
                canonical_type: "Pubkey",
                size: 32,
                offset: 16,
                intent: FieldIntent::Custom,
            },
            FieldDescriptor {
                name: "amount",
                canonical_type: "u64",
                size: 8,
                offset: 48,
                intent: FieldIntent::Custom,
            },
            FieldDescriptor {
                name: "is_active",
                canonical_type: "bool",
                size: 1,
                offset: 56,
                intent: FieldIntent::Custom,
            },
        ];

        static LAYOUTS: &[LayoutManifest] = &[LayoutManifest {
            name: "vault",
            disc: 1,
            version: 1,
            layout_id: [0xAA, 0xBB, 0xCC, 0xDD, 0x11, 0x22, 0x33, 0x44],
            total_size: 64,
            field_count: 3,
            fields: FIELDS,
        }];

        static ARGS: &[ArgDescriptor] = &[ArgDescriptor {
            name: "amount",
            canonical_type: "u64",
            size: 8,
        }];

        static ACCOUNTS: &[AccountEntry] = &[
            AccountEntry {
                name: "authority",
                writable: false,
                signer: true,
                layout_ref: "",
            },
            AccountEntry {
                name: "vault",
                writable: true,
                signer: false,
                layout_ref: "vault",
            },
        ];

        static INSTRUCTIONS: &[InstructionDescriptor] = &[InstructionDescriptor {
            name: "deposit",
            tag: 0,
            args: ARGS,
            accounts: ACCOUNTS,
            capabilities: &["write"],
            policy_pack: "standard",
            receipt_expected: true,
        }];

        static EVENT_FIELDS: &[FieldDescriptor] = &[
            FieldDescriptor {
                name: "depositor",
                canonical_type: "Pubkey",
                size: 32,
                offset: 0,
                intent: FieldIntent::Custom,
            },
            FieldDescriptor {
                name: "amount",
                canonical_type: "u64",
                size: 8,
                offset: 32,
                intent: FieldIntent::Custom,
            },
        ];

        static EVENTS: &[EventDescriptor] = &[EventDescriptor {
            name: "deposit_event",
            tag: 0,
            fields: EVENT_FIELDS,
        }];

        ProgramManifest {
            name: "test_vault",
            version: "0.1.0",
            description: "A test vault program",
            layouts: LAYOUTS,
            layout_metadata: &[],
            instructions: INSTRUCTIONS,
            events: EVENTS,
            policies: &[],
            compatibility_pairs: &[],
            tooling_hints: &[],
            contexts: &[],
        }
    }

    #[test]
    fn ts_accounts_generates_interface() {
        let m = test_manifest();
        let output = TsAccounts(&m).to_string();
        assert!(output.contains("export interface Vault {"));
        assert!(output.contains("authority: PublicKey;"));
        assert!(output.contains("amount: bigint;"));
        assert!(output.contains("isActive: boolean;"));
    }

    #[test]
    fn ts_accounts_generates_decoder() {
        let m = test_manifest();
        let output = TsAccounts(&m).to_string();
        assert!(output.contains("export function decodeVault(data: Uint8Array)"));
        assert!(output.contains("export function decodeVault(data: Uint8Array): \n  Vault {\n  assertVaultLayout(data);"));
        assert!(
            output.contains("throw new Error(`Data too small for vault: ${data.length} < 64`);")
        );
        assert!(output.contains("new PublicKey(data.slice(16, 48))"));
        assert!(output.contains("view.getBigUint64(48, true)"));
        assert!(output.contains("data[56] !== 0"));
    }

    #[test]
    fn ts_accounts_generates_discriminator() {
        let m = test_manifest();
        let output = TsAccounts(&m).to_string();
        assert!(output.contains("export const VAULT_DISC = 1;"));
    }

    #[test]
    fn ts_instructions_generates_builder() {
        let m = test_manifest();
        let output = TsInstructions(&m).to_string();
        assert!(output.contains("export interface DepositArgs {"));
        assert!(output.contains("export interface DepositAccounts {"));
        assert!(output.contains("export function createDepositInstruction("));
        assert!(output.contains("data[0] = 0; // instruction discriminator"));
        assert!(output.contains("view.setBigUint64(1, args.amount, true);"));
    }

    #[test]
    fn ts_instructions_account_meta() {
        let m = test_manifest();
        let output = TsInstructions(&m).to_string();
        assert!(output.contains("accounts.authority, isSigner: true, isWritable: false"));
        assert!(output.contains("accounts.vault, isSigner: false, isWritable: true"));
    }

    #[test]
    fn ts_events_generates_decoder() {
        let m = test_manifest();
        let output = TsEvents(&m).to_string();
        assert!(output.contains("export interface DepositEventEvent {"));
        assert!(output.contains("export function decodeDepositEventEvent(data: Uint8Array)"));
        assert!(output.contains("DEPOSIT_EVENT_EVENT_DISC = 0;"));
    }

    #[test]
    fn ts_types_generates_header() {
        let m = test_manifest();
        let output = TsTypes(&m).to_string();
        assert!(output.contains("export interface HopperHeader {"));
        assert!(output.contains("export function decodeHeader(data: Uint8Array)"));
        assert!(output.contains("flags: view.getUint16(2, true),"));
        assert!(output.contains(
            "layoutId: data.slice(LAYOUT_ID_OFFSET, LAYOUT_ID_OFFSET + LAYOUT_ID_LENGTH),"
        ));
        assert!(output.contains("reserved: data.slice(12, 16),"));
        assert!(output.contains("Vault: 1,"));
    }

    #[test]
    fn ts_decode_header_and_assert_layout_id_share_offset() {
        let m = test_manifest();
        let accounts = TsAccounts(&m).to_string();
        let types = TsTypes(&m).to_string();
        assert!(accounts.contains("export const LAYOUT_ID_OFFSET = 4;"));
        assert!(accounts.contains("data[LAYOUT_ID_OFFSET + i]"));
        assert!(types.contains("const LAYOUT_ID_OFFSET = 4;"));
        assert!(types.contains("data.slice(LAYOUT_ID_OFFSET, LAYOUT_ID_OFFSET + LAYOUT_ID_LENGTH)"));
        assert!(!types.contains("data.slice(2, 10)"));
    }

    #[test]
    fn ts_index_reexports_all() {
        let m = test_manifest();
        let output = TsIndex(&m).to_string();
        assert!(output.contains("export * from \"./types\";"));
        assert!(output.contains("export * from \"./accounts\";"));
        assert!(output.contains("export * from \"./instructions\";"));
        assert!(output.contains("export * from \"./events\";"));
    }

    #[test]
    fn ts_full_client_gen_has_all_sections() {
        let m = test_manifest();
        let output = TsClientGen(&m).to_string();
        assert!(output.contains("=== types.ts ==="));
        assert!(output.contains("=== accounts.ts ==="));
        assert!(output.contains("=== instructions.ts ==="));
        assert!(output.contains("=== events.ts ==="));
        assert!(output.contains("=== index.ts ==="));
    }

    #[test]
    fn ts_accounts_emits_layout_id_constants_and_assertion_helpers() {
        let m = test_manifest();
        let output = TsAccounts(&m).to_string();
        // Generic helper and offset constants are always present.
        assert!(output.contains("export const LAYOUT_ID_OFFSET = 4;"));
        assert!(output.contains("export const LAYOUT_ID_LENGTH = 8;"));
        assert!(output.contains(
            "export function assertLayoutId(data: Uint8Array, expectedHex: string): void"
        ));
        // Per-layout const + assertion with the real 16-hex-char id.
        assert!(output.contains("export const VAULT_LAYOUT_ID = \"aabbccdd11223344\";"));
        assert!(output.contains("export function assertVaultLayout(data: Uint8Array): void"));
        assert!(output.contains("assertLayoutId(data, VAULT_LAYOUT_ID);"));
    }

    #[test]
    fn ts_assert_layout_id_handles_short_buffer_check() {
        let m = test_manifest();
        let output = TsAccounts(&m).to_string();
        // The guard explicitly rejects buffers shorter than the
        // header so callers cannot accidentally trust a truncated
        // slice.
        assert!(output.contains("if (data.length < HEADER_SIZE)"));
        assert!(output.contains("throw new Error"));
    }

    #[test]
    fn ts_data_size_calculation() {
        static ARGS: &[ArgDescriptor] = &[
            ArgDescriptor {
                name: "amount",
                canonical_type: "u64",
                size: 8,
            },
            ArgDescriptor {
                name: "bump",
                canonical_type: "u8",
                size: 1,
            },
        ];
        let ix = InstructionDescriptor {
            name: "test",
            tag: 0,
            args: ARGS,
            accounts: &[],
            capabilities: &[],
            policy_pack: "",
            receipt_expected: false,
        };
        // 1 (disc) + 8 (u64) + 1 (u8) = 10
        assert_eq!(instruction_data_size(&ix), 10);
    }

    // -- Kotlin generator tests --

    #[test]
    fn kt_accounts_generates_data_class() {
        let m = test_manifest();
        let output = KtAccounts(&m).to_string();
        assert!(output.contains("data class Vault("));
        assert!(output.contains("val authority: PublicKey"));
        assert!(output.contains("val amount: ULong"));
        assert!(output.contains("val isActive: Boolean"));
    }

    #[test]
    fn kt_accounts_generates_decoder() {
        let m = test_manifest();
        let output = KtAccounts(&m).to_string();
        assert!(output.contains("fun decodeVault(data: ByteArray): Vault {"));
        assert!(output.contains("PublicKey(data.copyOfRange(16, 48))"));
        assert!(output.contains("ByteBuffer.wrap(data, 48, 8)"));
        assert!(output.contains("data[56] != 0.toByte()"));
    }

    #[test]
    fn kt_accounts_generates_discriminator() {
        let m = test_manifest();
        let output = KtAccounts(&m).to_string();
        assert!(output.contains("const val VAULT_DISC: Byte = 1"));
    }

    #[test]
    fn kt_accounts_emits_layout_id_constants_and_assertion_helpers() {
        let m = test_manifest();
        let output = KtAccounts(&m).to_string();
        // Generic helper and offset constants are always present.
        assert!(output.contains("const val HEADER_SIZE: Int = 16"));
        assert!(output.contains("const val LAYOUT_ID_OFFSET: Int = 4"));
        assert!(output.contains("const val LAYOUT_ID_LENGTH: Int = 8"));
        assert!(output.contains("fun assertLayoutId(data: ByteArray, expectedHex: String) {"));
        // Per-layout const + assertion with the real 16-hex-char id.
        assert!(output.contains("const val VAULT_LAYOUT_ID: String = \"aabbccdd11223344\""));
        assert!(output.contains("fun assertVaultLayout(data: ByteArray) {"));
        assert!(output.contains("assertLayoutId(data, VAULT_LAYOUT_ID)"));
        // Decoder calls the assertion first so a mismatched account
        // fails with LayoutMismatchException instead of decoding garbage.
        assert!(output
            .contains("fun decodeVault(data: ByteArray): Vault {\n    assertVaultLayout(data)"));
    }

    #[test]
    fn kt_instructions_generates_builder() {
        let m = test_manifest();
        let output = KtInstructions(&m).to_string();
        assert!(output.contains("data class DepositArgs("));
        assert!(output.contains("data class DepositAccounts("));
        assert!(output.contains("fun createDepositInstruction("));
        assert!(output.contains("data[0] = 0.toByte() // instruction discriminator"));
    }

    #[test]
    fn kt_instructions_account_meta() {
        let m = test_manifest();
        let output = KtInstructions(&m).to_string();
        assert!(output.contains("isSigner = true, isWritable = false"));
        assert!(output.contains("isSigner = false, isWritable = true"));
    }

    #[test]
    fn kt_events_generates_decoder() {
        let m = test_manifest();
        let output = KtEvents(&m).to_string();
        assert!(output.contains("data class DepositEventEvent("));
        assert!(output.contains("fun decodeDepositEventEvent(data: ByteArray)"));
        assert!(output.contains("DEPOSIT_EVENT_EVENT_DISC: Byte = 0"));
    }

    #[test]
    fn kt_types_generates_header() {
        let m = test_manifest();
        let output = KtTypes(&m).to_string();
        assert!(output.contains("data class HopperHeader("));
        assert!(output.contains("fun decodeHeader(data: ByteArray): HopperHeader {"));
        assert!(output.contains(
            "flags = ByteBuffer.wrap(data, 2, 2).order(ByteOrder.LITTLE_ENDIAN).short.toUShort(),"
        ));
        assert!(output.contains("layoutId = data.copyOfRange(TYPES_LAYOUT_ID_OFFSET, TYPES_LAYOUT_ID_OFFSET + TYPES_LAYOUT_ID_LENGTH),"));
        assert!(output.contains("reserved = data.copyOfRange(12, 16)"));
        assert!(!output.contains("data.copyOfRange(2, 10)"));
        assert!(output.contains("VAULT: Byte = 1"));
    }

    #[test]
    fn kt_full_client_gen_has_all_sections() {
        let m = test_manifest();
        let output = KtClientGen(&m).to_string();
        assert!(output.contains("=== Types.kt ==="));
        assert!(output.contains("=== Accounts.kt ==="));
        assert!(output.contains("=== Instructions.kt ==="));
        assert!(output.contains("=== Events.kt ==="));
    }
}