#include "lib.h"

#include "buffer.h"

#include "str.h"

#include "istream.h"

#include "mail-html2text.h"

#include "message-parser.h"

#include "message-decoder.h"

#include "message-snippet.h"

enum snippet_state {

/* beginning of the line */

SNIPPET_STATE_NEWLINE = 0,

/* within normal text */

SNIPPET_STATE_NORMAL,

/* within quoted text - skip until EOL */

SNIPPET_STATE_QUOTED

};

struct snippet_context {

string_t *snippet;

unsigned int chars_left;

enum snippet_state state;

bool add_whitespace;

struct mail_html2text *html2text;

buffer_t *plain_output;

};

static bool snippet_generate(struct snippet_context *ctx,

const unsigned char *data, size_t size)

{

size_t i, count;

if (ctx->html2text != NULL) {

buffer_set_used_size(ctx->plain_output, 0);

mail_html2text_more(ctx->html2text, data, size,

ctx->plain_output);

data = ctx->plain_output->data;

size = ctx->plain_output->used;

}

/* message-decoder should feed us only valid and complete

for (i = 0; i < size; i += count) {

count = 1;

switch (ctx->state) {

case SNIPPET_STATE_NEWLINE:

if (data[i] == '>' && ctx->html2text == NULL) {

ctx->state = SNIPPET_STATE_QUOTED;

break;

}

ctx->state = SNIPPET_STATE_NORMAL;

/* fallthrough */

case SNIPPET_STATE_NORMAL:

if (size-i >= 3 &&

((data[i] == 0xEF && data[i+1] == 0xBB && data[i+2] == 0xBF) ||

(data[i] == 0xBF && data[i+1] == 0xBB && data[i+2] == 0xEF))) {

count += 2; /* because we skip +1 next */

break;

}

if (data[i] == '\r' || data[i] == '\n' ||

data[i] == '\t' || data[i] == ' ') {

/* skip any leading whitespace */

if (str_len(ctx->snippet) > 1)

ctx->add_whitespace = TRUE;

if (data[i] == '\n')

ctx->state = SNIPPET_STATE_NEWLINE;

break;

}

if (ctx->add_whitespace) {

str_append_c(ctx->snippet, ' ');

ctx->add_whitespace = FALSE;

if (ctx->chars_left-- == 0)

return FALSE;

}

if (ctx->chars_left == 0)

return FALSE;

ctx->chars_left--;

count = uni_utf8_char_bytes(data[i]);

i_assert(i + count <= size);

str_append_n(ctx->snippet, data + i, count);

break;

case SNIPPET_STATE_QUOTED:

if (data[i] == '\n')

ctx->state = SNIPPET_STATE_NEWLINE;

break;

}

}

return TRUE;

}

int message_snippet_generate(struct istream *input,

unsigned int max_snippet_chars,

string_t *snippet)

{

struct message_parser_ctx *parser;

struct message_part *parts;

struct message_decoder_context *decoder;

struct message_block raw_block, block;

struct snippet_context ctx;

pool_t pool;

int ret;

i_zero(&ctx);

pool = pool_alloconly_create("message snippet", 1024);

ctx.snippet = snippet;

ctx.chars_left = max_snippet_chars;

parser = message_parser_init(pool_datastack_create(), input, 0, 0);

decoder = message_decoder_init(NULL, 0);

while ((ret = message_parser_parse_next_block(parser, &raw_block)) > 0) {

if (!message_decoder_decode_next_block(decoder, &raw_block, &block))

continue;

if (block.size == 0) {

const char *ct;

if (block.hdr != NULL)

continue;

/* end of headers - verify that we can use this

ct = message_decoder_current_content_type(decoder);

if (ct == NULL)

/* text/plain */ ;

else if (mail_html2text_content_type_match(ct)) {

ctx.html2text = mail_html2text_init(MAIL_HTML2TEXT_FLAG_SKIP_QUOTED);

ctx.plain_output = buffer_create_dynamic(pool, 1024);

} else if (strncasecmp(ct, "text/", 5) != 0)

break;

continue;

}

if (!snippet_generate(&ctx, block.data, block.size))

break;

}

i_assert(ret != 0);

message_decoder_deinit(&decoder);

message_parser_deinit(&parser, &parts);

mail_html2text_deinit(&ctx.html2text);

pool_unref(&pool);

return input->stream_errno == 0 ? 0 : -1;

}