import "@ffi/c"
import "@std/mem"
import "@std/arraylist"
import "@std/io"
import "@std/process"

import "@source/diagnostics"
import "@source/strpool"
import "@source/lexer"
import "@source/ast"
import "@source/parser"
import "@source/sema"
import "@source/ir"
import "@source/lower"
import "@source/interpreter"
typecheck :: import "@source/sema/check"

test import "@std/mem"
test import "@std/enummap"
test import "@std/arraylist"
test import "@std/hashmap"
test import "@std/strmap"
test import "@std/meta"
test import "@source/diagnostics"
test import "@source/strpool"
test import "@source/lexer"
test import "@source/ast"
test import "@source/parser"
test import "@source/sema"
test import "@source/sema/check"
test import "@source/lower"
test import "@source/interpreter"

@hide:file
DriverError :: alias (
    mem.AllocError
    | diagnostics.CapacityError
    | lexer.SourceError
    | strpool.InternError
    | io.OpenError
    | io.CloseError
    | io.ReadError
    | io.WriteError
)

main proc(init process.Init) i32 {
    return command(mem.c_allocator, init.io) catch |err| {
        if (process.argument(2)) |path| {
            io.print("{s}: infrastructure error: {s}\n", io.stderr(init.io), {
                argument_text(path), infrastructure_message(err),
            }) catch |_| {}
        } else {
            io.print("honey: infrastructure error: {s}\n", io.stderr(init.io), {
                infrastructure_message(err),
            }) catch |_| {}
        }
        return 2
    }
}

@hide:file
infrastructure_message proc(error DriverError) []u8 {
    return match error {
        .out_of_memory: "out of memory"
        .diagnostic_limit_reached: "diagnostic limit reached"
        .source_too_large: "source file is too large"
        .out_of_space: "identifier storage is full"
        .open_failed: "cannot open source file"
        .close_failed: "cannot close source file"
        .not_open_for_reading: "source file is not readable"
        .read_failed: "cannot read source file"
        .not_open_for_writing: "output is not writable"
        .write_failed: "cannot write output"
        .no_progress: "output writer made no progress"
    }
}

@hide:file
command proc(allocator mem.Allocator, runtime io.Io) i32 ! DriverError {
    if (process.argument_count() != 3) {
        try io.print("usage: honey run <file>\n", io.stderr(runtime), {})
        return 2
    }
    if (process.argument(1)) |operation| {
        if (!mem.eql(argument_text(operation), "run")) {
            try io.print("usage: honey run <file>\n", io.stderr(runtime), {})
            return 2
        }
    } else {
        return 2
    }
    if (process.argument(2)) |path| return try run_file(allocator, runtime, path)
    return 2
}

@hide:file
argument_text proc(pointer [*;0]u8) []u8 {
    length := usize(0)
    while (pointer[length] != 0) length += 1
    return pointer[..length]
}

@hide:file
read_source proc(allocator mem.Allocator, runtime io.Io, path [*;0]u8) arraylist.ArrayList(u8) ! DriverError {
    # bootstrap cannot construct a dynamic sentinel slice from argv's sentinel pointer.
    descriptor := c_int(-1)
    while true {
        descriptor = c.open(ptrcast!(path), c.O_RDONLY)
        if (descriptor >= 0) break
        if (c.__error()?^ != c.EINTR) return .open_failed
    }
    file :: io.File{ io = runtime, handle = io.Handle{ file_desc = descriptor } }
    closing := false
    defer {
        if (!closing) io.close(file) catch |_| {}
    }
    bytes := arraylist.init(u8, allocator)
    errdefer arraylist.deinit(&bytes)
    input :: io.reader(file)
    maximum :: usize(maxval!(u32))
    while true {
        length :: bytes.items.len
        if (length == maximum) {
            probe [1]mut u8 := undefined
            if (try io.read(input, (&probe)[..]) != 0) return .source_too_large
            break
        }
        if (length == bytes.capacity) {
            growth := usize(4096)
            if (growth > maximum - length) growth = maximum - length
            try arraylist.reserve(&bytes, length + growth)
        }
        storage :: bytes.items.ptr[..bytes.capacity]
        end := bytes.capacity
        if (end > maximum) end = maximum
        count :: try io.read(input, storage[length..end])
        if (count == 0) break
        bytes.items = storage[..length + count]
    }
    closing = true
    try io.close(file)
    return bytes
}

@hide:file
compile proc(allocator mem.Allocator, source []u8, diagnostic_store @mut diagnostics.Store) ir.Module ! DriverError {
    strpool.strings = strpool.init(allocator)
    defer strpool.deinit(&strpool.strings)
    scan_state := lexer.init(allocator)
    defer lexer.deinit(&scan_state)
    try lexer.scan(&scan_state, source, diagnostic_store)
    tree := try parser.parse(allocator, scan_state.tokens.items, source, diagnostic_store)
    defer ast.deinit(&tree)
    resolution := try sema.resolve(allocator, &tree, diagnostic_store)
    defer sema.deinit(&resolution)
    checked := try typecheck.check(allocator, &tree, &resolution, diagnostic_store)
    defer typecheck.deinit(&checked)
    return try lower.lower(allocator, &tree, &resolution, &checked, diagnostic_store)
}

@hide:file
run_file proc(allocator mem.Allocator, runtime io.Io, path [*;0]u8) i32 ! DriverError {
    source := try read_source(allocator, runtime, path)
    defer arraylist.deinit(&source)
    diagnostic_store := diagnostics.init(allocator)
    defer diagnostics.deinit(&diagnostic_store)
    module := try compile(allocator, source.items, &diagnostic_store)
    defer ir.deinit(&module)
    outcome :: try interpreter.run(allocator, &module, &diagnostic_store)
    if (outcome.trap == null) try print_result(io.stdout(runtime), outcome.value)
    try report_diagnostics(allocator, io.stderr(runtime), argument_text(path), source.items, &diagnostic_store, outcome.trap)
    if (outcome.trap != null or diagnostics.count(&diagnostic_store) != 0) return 1
    return 0
}

@hide:file
print_result proc(output io.Writer, value ir.Value) void ! io.WriteError {
    match value.type {
        .int: try io.print("{}\n", output, {value.data.integer})
        .float: try io.print("{d}\n", output, {value.data.real})
        .string: try io.print("{s}\n", output, {value.data.string})
        .void: {}
        else: unreachable
    }
}

@hide:file
report_diagnostics proc(
    allocator mem.Allocator,
    output io.Writer,
    path []u8,
    source []u8,
    diagnostic_store @diagnostics.Store,
    trap ?diagnostics.DiagnosticId,
) void ! (mem.AllocError | io.WriteError) {
    if (diagnostics.count(diagnostic_store) == 0) return
    starts := arraylist.init(usize, allocator)
    defer arraylist.deinit(&starts)
    try arraylist.append(&starts, usize(0))
    for (source) |byte, index| {
        if (byte == '\n') try arraylist.append(&starts, index + 1)
    }
    for (0..diagnostics.count(diagnostic_store)) |index| {
        if (diagnostics.get(diagnostic_store, diagnostics.DiagnosticId(index))) |diagnostic| {
            offset :: usize(diagnostic.span.start)
            line := usize(0)
            end := starts.items.len
            while (line + 1 < end) {
                middle :: line + divtrunc!(end - line, 2)
                if (starts.items[middle] <= offset) line = middle
                else end = middle
            }
            label []u8 := "error"
            if (trap) |id| {
                if (id == diagnostics.DiagnosticId(index)) label = "runtime trap"
            }
            try io.print("{s}:{}:{}: {s}: {s}\n", output, {
                path, line + 1, offset - starts.items[line] + 1, label, diagnostics.message(diagnostic.code),
            })
        }
    }
}