#!/usr/bin/env bash
# tools/lsp/build.sh — Build the El LSP server binary.
#
# Output: tools/lsp/dist/el-lsp
#
# Usage:
#   cd tools/lsp && ./build.sh
#   EL_HOME=/path/to/el ./build.sh        # if el root is elsewhere
#   ELC=/path/to/custom/elc ./build.sh    # use a specific compiler binary
#
# Prerequisites:
#   - elc binary (either on PATH or ELC env var)
#   - el-compiler/runtime/el_runtime.c
#   - cc (clang or gcc), libcurl, pthreads
#
# NOTE — seed primitive __read_n:
#   el-lsp.el calls __read_n(n: Int) -> String, which reads exactly n bytes
#   from stdin.  This primitive must be present in el_runtime.c and declared
#   in el_runtime.h for the compiled binary to work correctly.
#
#   Until __read_n is added to the runtime, the LSP will compile and link
#   successfully but lsp_read_message() will silently use the __read_n symbol
#   — causing a linker error.  The seed agent must:
#     1. Add el_val_t __read_n(el_val_t n) to el-compiler/runtime/el_runtime.c
#     2. Declare el_val_t __read_n(el_val_t n) in el-compiler/runtime/el_runtime.h
#     3. Add "__read_n" with arity 1 to the builtin_arity table in
#        el-compiler/src/codegen.el
#     4. Rebuild the elc binary
#
# Implementation sketch for __read_n in C:
#
#   el_val_t __read_n(el_val_t n) {
#       int64_t count = (int64_t)n;
#       if (count <= 0) return EL_STR("");
#       char* buf = malloc(count + 1);
#       if (!buf) return EL_STR("");
#       size_t total = 0;
#       while (total < (size_t)count) {
#           size_t got = fread(buf + total, 1, (size_t)count - total, stdin);
#           if (got == 0) break;
#           total += got;
#       }
#       buf[total] = '\0';
#       return EL_STR(buf);
#   }

set -euo pipefail
cd "$(dirname "$0")"

# ── Locate el root ─────────────────────────────────────────────────────────────
EL_HOME="${EL_HOME:-$(cd ../.. && pwd)}"
ELC="${ELC:-${EL_HOME}/dist/platform/elc}"
RUNTIME_DIR="${EL_HOME}/el-compiler/runtime"

# ── Validate prerequisites ─────────────────────────────────────────────────────
if [ ! -x "${ELC}" ]; then
    echo "error: elc not found at ${ELC}" >&2
    echo "       Set ELC=/path/to/elc or EL_HOME=/path/to/el-root" >&2
    exit 1
fi

if [ ! -f "${RUNTIME_DIR}/el_runtime.c" ]; then
    echo "error: el_runtime.c not found at ${RUNTIME_DIR}/el_runtime.c" >&2
    exit 1
fi

mkdir -p dist

# ── Concatenate runtime modules + LSP source ───────────────────────────────────
# Load order follows runtime/manifest.el: string → math → state → env →
# fs → exec → time → json → http → then our LSP source.
RUNTIME_SRCS=(
    "${EL_HOME}/runtime/string.el"
    "${EL_HOME}/runtime/math.el"
    "${EL_HOME}/runtime/state.el"
    "${EL_HOME}/runtime/env.el"
    "${EL_HOME}/runtime/fs.el"
    "${EL_HOME}/runtime/exec.el"
    "${EL_HOME}/runtime/time.el"
    "${EL_HOME}/runtime/json.el"
)

# Check that runtime modules exist
MISSING=0
for f in "${RUNTIME_SRCS[@]}"; do
    if [ ! -f "${f}" ]; then
        echo "warning: runtime module not found: ${f}" >&2
        MISSING=$((MISSING + 1))
    fi
done
if [ "${MISSING}" -gt 0 ]; then
    echo "error: ${MISSING} runtime module(s) missing — cannot build" >&2
    exit 1
fi

COMBINED="dist/el-lsp-combined.el"
echo "==> Combining sources..."
cat "${RUNTIME_SRCS[@]}" el-lsp.el > "${COMBINED}"
echo "    ${COMBINED}"

# ── Compile El → C ─────────────────────────────────────────────────────────────
C_OUT="dist/el-lsp.c"
echo "==> Compiling El → C..."
"${ELC}" "${COMBINED}" > "${C_OUT}"
echo "    ${C_OUT}"

# ── Compile C → binary ─────────────────────────────────────────────────────────
BIN="dist/el-lsp"
echo "==> Compiling C → binary..."
cc -std=c11 -O2 \
    -I "${RUNTIME_DIR}" \
    -o "${BIN}" \
    "${C_OUT}" "${RUNTIME_DIR}/el_runtime.c" \
    -lcurl -lpthread
echo "    ${BIN}"

echo
echo "==> Build complete: ${BIN}"
echo
echo "    Run as LSP server (editors connect via stdin/stdout):"
echo "    ${BIN}"
echo
echo "    Test with a synthetic LSP initialize request:"
echo "    echo -e 'Content-Length: 97\\r\\n\\r\\n{\"jsonrpc\":\"2.0\",\"id\":1,\"method\":\"initialize\",\"params\":{\"capabilities\":{}}}' | ${BIN}"